Intermediate film for laminated glass and laminated glass

ABSTRACT

Provided is an interlayer film for laminated glass with which double images in laminated glass can be significantly suppressed. The interlayer film for laminated glass according to the present invention is an interlayer film for use in a laminated glass that is a head-up display, the interlayer film has one end, and the other end being at the opposite side of the one end, the other end has a thickness larger than a thickness of the one end, the interlayer film has a region for display corresponding to a display region of the head-up display, and when three regions obtained by equally dividing the region for display into three in a direction connecting the one end and the other end are named a first partial region for display, a second partial region for display, and a third partial region for display in sequence from the one end side, as to partial wedge angle A x , B x , and C x  in the first, second, and third partial regions for display, and partial wedge angle φ x  in the region for display satisfy, |A x −φ x | is 0.05 mrad or less, |B x −φ x | is 0.05 mrad or less, and |C x −φ x | is 0.05 mrad or less.

TECHNICAL FIELD

The present invention relates to an interlayer film for laminated glasswhich is used for obtaining laminated glass. Moreover, the presentinvention relates to a laminated glass prepared with the interlayer filmfor laminated glass.

BACKGROUND ART

Since laminated glass generally generates only a small amount ofscattering glass fragments even when subjected to external impact andbroken, laminated glass is excellent in safety. As such, the laminatedglass is widely used for automobiles, railway vehicles, aircraft, ships,buildings and the like. The laminated glass is produced by sandwichingan interlayer film for laminated glass between a pair of glass plates.

Moreover, as the laminated glass used for automobiles, a head-up display(HUD) has been known. In a HUD, it is possible to display measuredinformation including automobile traveling data such as speed on thewindshield of the automobile, and the driver can recognize as if thedisplay were shown in front of the windshield.

In the HUD, there is a problem that the measured information or the likeis doubly observed.

In order to suppress double images, a wedge-like shaped interlayer filmhas been used. The following Patent Document 1 discloses a sheet oflaminated glass in which a wedge-like shaped interlayer film having aprescribed wedge angle is sandwiched between a pair of glass plates. Insuch a laminated glass, by the adjustment of the wedge angle of theinterlayer film, a display of measured information reflected by oneglass plate and a display of measured information reflected by anotherglass plate can be focused into one point to make an image in the visualfield of a driver. As such, the display of measured information is hardto be observed doubly and the visibility of a driver is hardly hindered.

RELATED ART DOCUMENT Patent Document

-   Patent Document 1: JP H4-502525 T

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In conventional interlayer films, it is difficult to sufficientlysuppress double images. Investigation carried out by the presentinventors led to the finding that only controlling a wedge angle cannotsufficiently suppress double images.

The present invention is aimed at providing an interlayer film forlaminated glass capable of significantly suppressing double images inthe laminated glass. Moreover, the present invention is also aimed atproviding laminated glass prepared with the above-mentioned interlayerfilm for laminated glass.

Means for Solving the Problems

According to a broad aspect of the present invention, there is providedan interlayer film for laminated glass (in this specification,“interlayer film for laminated glass” is sometimes abbreviated as“interlayer film”) for use in a laminated glass that is a head-updisplay, the interlayer film having one end, and the other end being atthe opposite side of the one end, the other end having a thicknesslarger than a thickness of the one end, the interlayer film having aregion for display corresponding to a display region of the head-updisplay, when three regions obtained by equally dividing the region fordisplay into three in a direction connecting the one end and the otherend are named a first partial region for display, a second partialregion for display, and a third partial region for display in sequencefrom the one end side, an absolute value of difference between partialwedge angle A_(x) in the first partial region for display, and partialwedge angle φ_(x) in the region for display being 0.05 mrad or less, anabsolute value of difference between partial wedge angle B_(x) in thesecond partial region for display and partial wedge angle φ_(x) in theregion for display being 0.05 mrad or less, an absolute value ofdifference between partial wedge angle C_(x) in the third partial regionfor display and partial wedge angle φ_(x) in the region for displaybeing 0.05 mrad or less.

According to a broad aspect of the present invention, there is providedan interlayer film for laminated glass (in this specification,“interlayer film for laminated glass” is sometimes abbreviated as“interlayer film”) having one end, and the other end being at theopposite side of the one end, the other end having a thickness largerthan a thickness of the one end, when a region between a position of 10cm and a position of 59.5 cm from the one end toward the other end ofthe interlayer film is named a region R, a region between a position of10 cm and a position of 26.5 cm from the one end toward the other end ofthe interlayer film is named a first partial region, a region between aposition of 26.5 cm and a position of 43 cm from the one end toward theother end of the interlayer film is named a second partial region, and aregion between a position of 43 cm and a position of 59.5 cm from theone end toward the other end of the interlayer film is named a thirdpartial region, an absolute value of difference between partial wedgeangle A_(y) in the first partial region and partial wedge angle φ_(y) inthe region R being 0.05 mrad or less, an absolute value of differencebetween partial wedge angle B_(y) in the second partial region andpartial wedge angle φ_(y) in the region R being 0.05 mrad or less, anabsolute value of difference between partial wedge angle C_(y) in thethird partial region and partial wedge angle φ_(y) in the region R being0.05 mrad or less.

In a specific aspect of the interlayer film according to the presentinvention, the interlayer film as a whole has a wedge angle θ of 0.05mrad or more.

In a specific aspect of the interlayer film according to the presentinvention, the interlayer film contains a thermoplastic resin.

In a specific aspect of the interlayer film according to the presentinvention, the interlayer film contains a plasticizer.

In a specific aspect of the interlayer film according to the presentinvention, the interlayer film includes a first layer and a second layerarranged on a first surface side of the first layer.

In a specific aspect of the interlayer film according to the presentinvention, the first layer contains a polyvinyl acetal resin, the secondlayer contains a polyvinyl acetal resin, and the content of the hydroxylgroup of the polyvinyl acetal resin in the first layer is lower than thecontent of the hydroxyl group of the polyvinyl acetal resin in thesecond layer.

In a specific aspect of the interlayer film according to the presentinvention, the first layer contains a polyvinyl acetal resin, the secondlayer contains a polyvinyl acetal resin, the first layer contains aplasticizer, the second layer contains a plasticizer, and the content ofthe plasticizer in the first layer relative to 100 parts by weight ofthe polyvinyl acetal resin in the first layer is larger than the contentof the plasticizer in the second layer relative to 100 parts by weightof the polyvinyl acetal resin in the second layer.

According to a broad aspect of the present invention, there is provideda laminated glass that is a head-up display, the laminated glass havingone end, and the other end being at the opposite side of the one end,the other end having a thickness larger than a thickness of the one end,the laminated glass having a display region of the head-up display, thelaminated glass including: a first lamination glass member, a secondlamination glass member, and an interlayer film arranged between thefirst lamination glass member and the second lamination glass member,the interlayer film having a region for display corresponding to thedisplay region, when three regions obtained by equally dividing theregion for display into three in a direction connecting the one end andthe other end are named a first partial region for display, a secondpartial region for display, and a third partial region for display insequence from the one end side, an absolute value of difference betweenpartial wedge angle A_(x) of the interlayer film in the first partialregion for display, and partial wedge angle φ_(x) of the interlayer filmin the region for display being 0.05 mrad or less, an absolute value ofdifference between partial wedge angle B_(x) of the interlayer film inthe second partial region for display and partial wedge angle φ_(x) ofthe interlayer film in the region for display being 0.05 mrad or less,an absolute value of difference between partial wedge angle C_(x) of theinterlayer film in the third partial region for display and partialwedge angle φ_(x) of the interlayer film in the region for display being0.05 mrad or less.

According to a broad aspect of the present invention, there is provideda laminated glass having one end, and the other end being at theopposite side of the one end, the other end having a thickness largerthan a thickness of the one end, the laminated glass including: a firstlamination glass member, a second lamination glass member, and aninterlayer film arranged between the first lamination glass member andthe second lamination glass member, when a region between a position of10 cm and a position of 59.5 cm from the one end toward the other end ofthe interlayer film is named a region R, a position of 10 cm and aposition of 26.5 cm from the one end toward the other end of theinterlayer film is named a first partial region, a region between aposition of 26.5 cm and a position of 43 cm from the one end toward theother end of the interlayer film is named a second partial region, and aregion between a position of 43 cm and a position of 59.5 cm from theone end toward the other end of the interlayer film is named a thirdpartial region, an absolute value of difference between partial wedgeangle A_(y) of the interlayer film in the first partial region andpartial wedge angle φ_(y) of the interlayer film in the region R being0.05 mrad or less, an absolute value of difference between partial wedgeangle B_(y) of the interlayer film in the second partial region andpartial wedge angle φ_(y) of the interlayer film in the region R being0.05 mrad or less, an absolute value of difference between partial wedgeangle C_(y) of the interlayer film in the third partial region andpartial wedge angle φ_(y) of the interlayer film in the region R being0.05 mrad or less.

In a specific aspect of the laminated glass according to the presentinvention, the interlayer film as a whole has a wedge angle θ of 0.05mrad or more.

In a specific aspect of the laminated glass according to the presentinvention, the first lamination glass member has a wedge angle of 0.05mrad or more.

In a specific aspect of the laminated glass according to the presentinvention, the second lamination glass member has a wedge angle of 0.05mrad or more.

Effect of the Invention

The interlayer film for laminated glass according to the presentinvention is an interlayer film for laminated glass for use in alaminated glass that is a head-up display. The interlayer film forlaminated glass according to the present invention has one end and theother end being at the opposite side of the one end, and the other endhas a thickness that is larger than a thickness of the one end. Theinterlayer film for laminated glass according to the present inventionhas a region for display corresponding to a display region of a head-updisplay. In the interlayer film for laminated glass according to thepresent invention, three regions obtained by equally dividing the regionfor display into three in a direction connecting the one end and theother end are named a first partial region for display, a second partialregion for display, and a third partial region for display in sequencefrom the one end side. In the interlayer film for laminated glassaccording to the present invention, an absolute value of differencebetween partial wedge angle A_(x) in the first partial region fordisplay, and partial wedge angle φ_(x) in the region for display is 0.05mrad or less. In the interlayer film for laminated glass according tothe present invention, an absolute value of difference between partialwedge angle B_(x) in the second partial region for display and partialwedge angle φ_(x) in the region for display is 0.05 mrad or less. In theinterlayer film for laminated glass according to the present invention,an absolute value of difference between partial wedge angle C_(x) in thethird partial region for display and partial wedge angle φ_(x) in theregion for display is 0.05 mrad or less. Since the interlayer film forlaminated glass according to the present invention has the aboveconfiguration, it is possible to significantly suppress double images inthe laminated glass.

The interlayer film for laminated glass according to the presentinvention has one end and the other end being at the opposite side ofthe one end, and the other end has a thickness that is larger than athickness of the one end. In the interlayer film for laminated glassaccording to the present invention, a region between a position of 10 cmand a position of 59.5 cm from the one end toward the other end of theinterlayer film is named a region R. In the interlayer film forlaminated glass according to the present invention, a region between aposition of 10 cm and a position of 26.5 cm from the one end toward theother end of the interlayer film is named a first partial region. In theinterlayer film for laminated glass according to the present invention,a region from the position of 26.5 cm to the position of 43 cm from theone end toward the other end of the interlayer film is named a secondpartial region. In the interlayer film for laminated glass according tothe present invention, a region between a position of 43 cm and aposition of 59.5 cm from the one end toward the other end of theinterlayer film is named a third partial region. In the interlayer filmfor laminated glass according to the present invention, an absolutevalue of difference between partial wedge angle A_(y) in the firstpartial region, and partial wedge angle φ_(y) in the region R is 0.05mrad or less. In the interlayer film for laminated glass according tothe present invention, an absolute value of difference between partialwedge angle B_(y) in the second partial region, and partial wedge angleφ_(y) in the region R is 0.05 mrad or less. In the interlayer film forlaminated glass according to the present invention, an absolute value ofdifference between partial wedge angle C_(y) in the third partialregion, and partial wedge angle φ_(y) in the region R is 0.05 mrad orless. Since the interlayer film for laminated glass according to thepresent invention has the above configuration, it is possible tosignificantly suppress double images in the laminated glass.

The laminated glass according to the present invention is a laminatedglass that is a head-up display. The laminated glass according to thepresent invention has one end and the other end being at the oppositeside of the one end, and the other end has a thickness that is largerthan a thickness of the one end. The laminated glass according to thepresent invention has a display region of the head-up display. Thelaminated glass according to the present invention includes a firstlamination glass member, a second lamination glass member, and aninterlayer film arranged between the first lamination glass member andthe second lamination glass member. In the laminated glass according tothe present invention, the interlayer film has a region for displaycorresponding to the display region. In the laminated glass according tothe present invention, three regions obtained by equally dividing theregion for display into three in a direction connecting the one end andthe other end are named a first partial region for display, a secondpartial region for display, and a third partial region for display insequence from the one end side. In the laminated glass according to thepresent invention, an absolute value of difference between partial wedgeangle A_(x) of the interlayer film in the first partial region fordisplay, and partial wedge angle φ_(x) of the interlayer film in theregion for display is 0.05 mrad or less. In the laminated glassaccording to the present invention, an absolute value of differencebetween partial wedge angle B_(x) of the interlayer film in the secondpartial region for display, and partial wedge angle φ_(x) of theinterlayer film in the region for display is 0.05 mrad or less. In thelaminated glass according to the present invention, an absolute value ofdifference between partial wedge angle C_(x) of the interlayer film inthe third partial region for display, and partial wedge angle φ_(x) ofthe interlayer film in the region for display is 0.05 mrad or less.Since the laminated glass according to the present invention is providedwith the above-mentioned configurations, it is possible to significantlysuppress double images.

The laminated glass according to the present invention has one end andthe other end being at the opposite side of the one end, and the otherend has a thickness that is larger than a thickness of the one end. Thelaminated glass according to the present invention includes a firstlamination glass member, a second lamination glass member, and aninterlayer film arranged between the first lamination glass member andthe second lamination glass member. In the laminated glass according tothe present invention, a region between a position of 10 cm and aposition of 59.5 cm from the one end toward the other end of theinterlayer film is named a region R. In the laminated glass according tothe present invention, a region between a position of 10 cm and aposition of 26.5 cm from the one end toward the other end of theinterlayer film is named a first partial region. In the laminated glassaccording to the present invention, a region between a position of 26.5cm and a position of 43 cm from the one end toward the other end of theinterlayer film is named a second partial region. In the laminated glassaccording to the present invention, a region between a position of 43 cmand a position of 59.5 cm from the one end toward the other end of theinterlayer film is named a third partial region. In the laminated glassaccording to the present invention, an absolute value of differencebetween partial wedge angle A_(y) of the interlayer film in the firstpartial region, and partial wedge angle φ_(y) of the interlayer film inthe region R is 0.05 mrad or less. In the laminated glass according tothe present invention, an absolute value of difference between partialwedge angle B_(y) of the interlayer film in the second partial region,and partial wedge angle φ_(y) of the interlayer film in the region R is0.05 mrad or less. In the laminated glass according to the presentinvention, an absolute value of difference between partial wedge angleC_(y) of the interlayer film in the third partial region, and partialwedge angle φ_(y) of the interlayer film in the region R is 0.05 mrad orless. Since the laminated glass according to the present invention isprovided with the above-mentioned configurations, it is possible tosignificantly suppress double images.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1(a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass, inaccordance with a first embodiment of the present invention.

FIGS. 2(a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass, inaccordance with a second embodiment of the present invention.

FIG. 3 is a sectional view schematically showing an interlayer film forlaminated glass in accordance with a third embodiment of the presentinvention.

FIG. 4 is a sectional view schematically showing an interlayer film forlaminated glass in accordance with a fourth embodiment of the presentinvention.

FIG. 5 is a sectional view schematically showing an interlayer film forlaminated glass in accordance with a fifth embodiment of the presentinvention.

FIG. 6 is a sectional view schematically showing an interlayer film forlaminated glass in accordance with a sixth embodiment of the presentinvention.

FIG. 7 is a sectional view showing an example of laminated glassprepared with the interlayer film for laminated glass shown in FIG. 1 .

FIG. 8 is a perspective view schematically showing a roll body preparedby winding the interlayer film for laminated glass shown in FIG. 1 .

FIG. 9 is a figure for explaining a preliminary pressing method used inevaluation of double images in Examples.

FIG. 10 is a figure showing the relationship between the distance fromthe one end of the interlayer film and the deviated thickness.

MODES FOR CARRYING OUT THE INVENTION

Hereinafter, the details of the present invention will be described.

The interlayer film for laminated glass (in the present specification,sometimes abbreviated as “interlayer film”) according to the presentinvention is used for laminated glass.

The laminated glass according to the present invention includes a firstlamination glass member, a second lamination glass member, and aninterlayer film arranged between the first lamination glass member andthe second lamination glass member.

The interlayer film according to the present invention, and theinterlayer film used in the laminated glass according to the presentinvention have a one-layer structure or a two or more-layer structure.The interlayer film according to the present invention, and theinterlayer film used in the laminated glass according to the presentinvention may have a one-layer structure or may have a two or more-layerstructure. The interlayer film according to the present invention, andthe interlayer film used in the laminated glass according to the presentinvention may have a two-layer structure, may have a two or more-layerstructure, may have a three-layer structure or may have a three ormore-layer structure. The interlayer film according to the presentinvention, and the interlayer film used in the laminated glass accordingto the present invention may be a single-layered interlayer film or maybe a multi-layered interlayer film.

The interlayer film according to the present invention has one end andthe other end being at the opposite side of the one end. The one end andthe other end are end parts of both sides facing each other in theinterlayer film. In the interlayer film according to the presentinvention, the thickness of the other end is larger than the thicknessof the one end.

The laminated glass according to the present invention has one end andthe other end being at the opposite side of the one end. The one end andthe other end are end parts of both sides facing each other in thelaminated glass. In the laminated glass according to the presentinvention, the other end has a thickness that is larger than a thicknessof the one end.

The one ends of the first lamination glass member, the second laminationglass member and the interlayer film are at the side of the one end ofthe laminated glass. The other ends of the first lamination glassmember, the second lamination glass member and the interlayer film areat the side of the other end of the laminated glass.

The interlayer film according to the present invention is used, forexample, in a laminated glass that is a head-up display.

The laminated glass according to the present invention is, for example,a head-up display.

The interlayer film according to the present invention, and theinterlayer film used in the laminated glass according to the presentinvention has, for example, a region for display corresponding to adisplay region of a head-up display. The region for display is a regioncapable of favorably displaying information. A preferred range of theregion for display will be described later.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, three regions obtained by equally dividing the region fordisplay into three in a direction connecting the one end and the otherend are named a first partial region for display, a second partialregion for display, and a third partial region for display in sequencefrom the one end side. In the region for display, the first partialregion for display is located on the one end side. In the region fordisplay, the second partial region for display is located between thefirst partial region for display and the third partial region fordisplay. In the region for display, the third partial region for displayis located on the other end side.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, the following partial wedge angle φ_(x), partial wedge angleA_(x), partial wedge angle B_(x), and partial wedge angle C_(x) arecalculated.

Partial wedge angle φ_(x) is a partial wedge angle in the region fordisplay.

Partial wedge angle φ_(x) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the region fordisplay.

Specifically, partial wedge angle φ_(x) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the region for display and terminating at the endpart of the other end side of the region for display.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle φ_(x).

Partial wedge angle A_(x) is a partial wedge angle in the first partialregion for display.

Partial wedge angle A_(x) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the firstpartial region for display.

Specifically, partial wedge angle A_(x) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the first partial region for display andterminating at the end part of the other end side of the first partialregion for display.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle A_(x).

Partial wedge angle B_(x) is a partial wedge angle in the second partialregion for display.

Partial wedge angle B_(x) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the secondpartial region for display.

Specifically, partial wedge angle B_(x) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the second partial region for display andterminating at the end part of the other end side of the second partialregion for display.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle B_(x).

Partial wedge angle C_(x) is a partial wedge angle in the third partialregion for display.

Partial wedge angle C_(x) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the thirdpartial region for display.

Specifically, partial wedge angle C_(x) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the third partial region for display andterminating at the end part of the other end side of the third partialregion for display.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle C_(x).

In the above “1:” in measurement of partial wedge angle φ_(x), partialwedge angle A_(x), partial wedge angle B_(x), and partial wedge angleC_(x), points are selected up to the position where selection of pointsat 2-mm intervals can be made from the one end side toward the other endside (positions of which interval is not less than 2 mm).

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, an absolute value of difference between partial wedge anglesA_(x) and partial wedge angle φ_(x) is 0.05 mrad or less. If theabsolute value of difference between partial wedge angle A_(x) andpartial wedge angle φ_(x) is more than 0.05 mrad, double images can begenerated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between partial wedge angle A_(x) and partial wedgeangle mx is preferably 0.04 mrad or less, more preferably 0.03 mrad orless. From the viewpoint of effectively suppressing double images,especially from the viewpoint of effectively suppressing double imagesregardless of the seated height of the observer, an absolute value ofdifference between partial wedge angle A_(x) and partial wedge angle ixis preferably more than 0 mrad, more preferably 0.01 mrad or more.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, an absolute value of difference between partial wedge anglesB_(x) and partial wedge angle φ_(x) is 0.05 mrad or less. If theabsolute value of difference between partial wedge angle B_(x) andpartial wedge angle φ_(x) is more than 0.05 mrad, double images can begenerated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between partial wedge angle B_(x) and partial wedgeangle φ_(x) is preferably 0.04 mrad or less, more preferably 0.03 mrador less.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, an absolute value of difference between partial wedge anglesC_(x) and partial wedge angle φ_(x) is 0.05 mrad or less. If theabsolute value of difference between partial wedge angle C_(x) andpartial wedge angle φ_(x) is more than 0.05 mrad, double images can begenerated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between partial wedge angle C_(x) and partial wedgeangle φ_(x) is preferably 0.04 mrad or less, more preferably 0.03 mrador less. From the viewpoint of effectively suppressing double images,especially from the viewpoint of effectively suppressing double imagesregardless of the seated height of the observer, an absolute value ofdifference between partial wedge angle C_(x) and partial wedge angleφ_(x) is preferably more than 0 mrad, more preferably 0.01 mrad or more.

From the viewpoint of suppressing double images more effectively, amongthree absolute values of difference: an absolute value of differencebetween partial wedge angle A_(x) and partial wedge angle φ_(x), anabsolute value of difference between partial wedge angle B_(x) andpartial wedge angle φ_(x) and an absolute value of difference betweenpartial wedge angle C_(x) and partial wedge angle φ_(x), it is preferredthat the absolute value of difference between partial wedge angle B_(x)and partial wedge angle φ_(x) be the smallest.

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that partial wedgeangle A_(x) be larger than partial wedge angle φ_(x).

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that partial wedgeangle C_(x) be smaller than partial wedge angle φ_(x).

From the viewpoint of suppressing double images more effectively,especially from the viewpoint of suppressing double images moreeffectively regardless of the seated height of the observer, it ispreferred that partial wedge angle A_(x) be larger than partial wedgeangle ox, and partial wedge angle C_(x) be smaller than partial wedgeangle φ_(x).

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle φ_(x) is preferably 0.8mrad or more, more preferably 0.9 mrad or more, and is preferably 1.2mrad or less, more preferably 1.1 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle φ_(x) is preferably 0.2 mrad ormore, more preferably 0.3 mrad or more, and is preferably 0.6 mrad orless, more preferably 0.5 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle A_(x) is preferably 1.0mrad or more, more preferably 1.1 mrad or more, and is preferably 1.4mrad or less, more preferably 1.3 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle A_(x) is preferably 0.4 mrad ormore, more preferably 0.5 mrad or more, and is preferably 0.8 mrad orless, more preferably 0.7 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle B_(x) is preferably 0.8mrad or more, more preferably 0.9 mrad or more, and is preferably 1.2mrad or less, more preferably 1.1 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle B_(x) is preferably 0.2 mrad ormore, more preferably 0.3 mrad or more, and is preferably 0.6 mrad orless, more preferably 0.5 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle C_(x) is preferably 0.6mrad or more, more preferably 0.7 mrad or more, and is preferably 1.0mrad or less, more preferably 0.9 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle C_(x) is preferably 0 mrad ormore, more preferably 0.1 mrad or more, and is preferably 0.4 mrad orless, more preferably 0.3 mrad or less.

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that partial wedgeangle A_(x) be the largest among the three partial wedge angles of thepartial wedge angle A_(x), partial wedge angle B_(x), and partial wedgeangle C_(x).

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that the partialwedge angle C_(x) be the smallest among the three partial wedge anglesof the partial wedge angle A_(x), partial wedge angle B_(x), and partialwedge angle C_(x).

From the viewpoint of suppressing double images more effectively,especially from the viewpoint of suppressing double images regardless ofthe seated height of the observer more effectively, it is preferred thatthe partial wedge angle A_(x) be the largest and the partial wedge angleC_(x) be the smallest among the three partial wedge angles of thepartial wedge angle A_(x), partial wedge angle B_(x), and partial wedgeangle C_(x).

In the interlayer film according to the present invention and theinterlayer film in the laminated glass according to the presentinvention, a region between a position of 10 cm and a position of 59.5cm from the one end toward the other end of the interlayer film is namedregion R. In the interlayer film according to the interlayer film andthe interlayer film in the laminated glass according to the presentinvention, a region between a position of 10 cm and a position of 26.5cm from the one end toward the other end of the interlayer film is nameda first partial region. In the interlayer film according to theinterlayer film and the interlayer film in the laminated glass accordingto the present invention, a region between a position of 26.5 cm and aposition of 43 cm from the one end toward the other end of theinterlayer film is named a second partial region. In the interlayer filmaccording to the interlayer film and the interlayer film in thelaminated glass according to the present invention, a region between aposition of 43 cm and a position of 59.5 cm from the one end toward theother end of the interlayer film is named a third partial region.

The first partial region, the second partial region, and the thirdpartial region are three regions obtained by equally dividing the regionR into three regions in the direction connecting the one end and theother end. In the region R, the first partial region is located on theone end side. In the region R, the second partial region is locatedbetween the first partial region and the third partial region. In theregion R, the third partial region is located on the other end side.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, the following partial wedge angle φ_(y), partial wedge angleA_(y), partial wedge angle B_(y), and partial wedge angle C_(y) arecalculated.

Partial wedge angle φ_(y) is a partial wedge angle in the region R.

Partial wedge angle φ_(y) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the region R.

Specifically, partial wedge angle φ_(y) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the region R and terminating at the end part ofthe other end side of the region R.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle φ_(y).

Partial wedge angle A_(y) is a partial wedge angle in the first partialregion.

Partial wedge angle A_(y) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the firstpartial region.

Specifically, partial wedge angle A_(y) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the first partial region and terminating at theend part of the other end side of the first partial region.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle A_(y).

Partial wedge angle B_(y) is a partial wedge angle in the second partialregion.

Partial wedge angle B_(y) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the secondpartial region.

Specifically, partial wedge angle B_(y) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the second partial region and terminating at theend part of the other end side of the second partial region.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle B_(y).

Partial wedge angle C_(y) is a partial wedge angle in the third partialregion for display.

Partial wedge angle C_(y) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in the thirdpartial region for display.

Specifically, partial wedge angle C_(y) is measured in the order of thefollowing 1 to 3.

1: Points P are selected at intervals of 2 mm starting at the end partof the one end side of the third partial region and terminating at theend part of the other end side of the third partial region.

2: At each point P, the thickness of the interlayer film is measured.

3: Plotting the distance (unit: mm) from the end part of the one endside of the interlayer film on the x axis, and the thickness (unit: μm)of the interlayer film on the y axis, a primary line is obtained by theleast-square method. The interior angle formed by the obtained primaryline and the line of y=0 is defined as partial wedge angle C_(y).

In the above “1:” in measurement of partial wedge angle φ_(y), partialwedge angle A_(y), partial wedge angle B_(y), and partial wedge angleC_(y), points are selected up to the position where selection of pointsat 2-mm intervals can be made from the one end side toward the other endside (positions of which interval is not less than 2 mm).

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, an absolute value of difference between partial wedge anglesA_(y) and partial wedge angle φ_(y) is 0.05 mrad or less. If theabsolute value of difference between partial wedge angle A_(y) andpartial wedge angle φ_(y) is more than 0.05 mrad, double images can begenerated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between partial wedge angle A_(y) and partial wedgeangle φ_(y) is preferably 0.04 mrad or less, more preferably 0.03 mrador less. From the viewpoint of effectively suppressing double images,especially from the viewpoint of effectively suppressing double imagesregardless of the seated height of the observer, an absolute value ofdifference between partial wedge angle A_(y) and partial wedge angleφ_(y) is preferably more than 0 mrad, more preferably 0.01 mrad or more.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, an absolute value of difference between partial wedge anglesB_(y) and partial wedge angle φ_(y) is 0.05 mrad or less. If theabsolute value of difference between partial wedge angle B_(y) andpartial wedge angle φ_(y) is more than 0.05 mrad, double images can begenerated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between partial wedge angle B_(y) and partial wedgeangle φ_(y) is preferably 0.04 mrad or less, more preferably 0.03 mrador less.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, an absolute value of difference between partial wedge angleC_(y) and partial wedge angle φ_(y) is 0.05 mrad or less. If theabsolute value of difference between partial wedge angle C_(y) andpartial wedge angle φ_(y) is more than 0.05 mrad, double images can begenerated.

From the viewpoint of effectively suppressing double images, an absolutevalue of difference between partial wedge angle C_(y) and partial wedgeangle φ_(y) is preferably 0.04 mrad or less, more preferably 0.03 mrador less. From the viewpoint of effectively suppressing double images,especially from the viewpoint of effectively suppressing double imagesregardless of the seated height of the observer, an absolute value ofdifference between partial wedge angle C_(y) and partial wedge angleφ_(y) is preferably more than 0 mrad, more preferably 0.01 mrad or more.

From the viewpoint of suppressing double images more effectively, amongthree absolute values of difference: an absolute value of differencebetween partial wedge angle A_(y) and partial wedge angle φ_(y), anabsolute value of difference between partial wedge angle B_(y) andpartial wedge angle φ_(y) and an absolute value of difference betweenpartial wedge angle C_(y) and partial wedge angle φ_(y), it is preferredthat the absolute value of difference between partial wedge angle B_(y)and partial wedge angle φ_(y) be the smallest.

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that partial wedgeangle A_(y) be larger than partial wedge angle φ_(y).

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that partial wedgeangle C_(y) be smaller than partial wedge angle θ y.

From the viewpoint of suppressing double images more effectively,especially from the viewpoint of suppressing double images moreeffectively regardless of the seated height of the observer, it ispreferred that partial wedge angle A_(y) be larger than partial wedgeangle φ_(y), and partial wedge angle C_(y) be smaller than partial wedgeangle φ_(y).

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle φ_(y) is preferably 0.8mrad or more, more preferably 0.9 mrad or more, and is preferably 1.2mrad or less, more preferably 1.1 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle φ_(y) is preferably 0.2 mrad ormore, more preferably 0.3 mrad or more, and is preferably 0.6 mrad orless, more preferably 0.5 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle A_(y) is preferably 1.0mrad or more, more preferably 1.1 mrad or more, and is preferably 1.4mrad or less, more preferably 1.3 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle A_(y) is preferably 0.4 mrad ormore, more preferably 0.5 mrad or more, and is preferably 0.8 mrad orless, more preferably 0.7 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle B_(y) is preferably 0.8mrad or more, more preferably 0.9 mrad or more, and is preferably 1.2mrad or less, more preferably 1.1 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle B_(y) is preferably 0.2 mrad ormore, more preferably 0.3 mrad or more, and is preferably 0.6 mrad orless, more preferably 0.5 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is large, suchas a truck or a bus, the partial wedge angle C_(y) is preferably 0.6mrad or more, more preferably 0.7 mrad or more, and is preferably 1.0mrad or less, more preferably 0.9 mrad or less.

From the viewpoint of effectively suppressing double images, and fromthe viewpoint of favorably obtaining a laminated glass suited for avehicle in which the attachment angle of the windshield is small, suchas a sports car, the partial wedge angle C_(y) is preferably 0 mrad ormore, more preferably 0.1 mrad or more, and is preferably 0.4 mrad orless, more preferably 0.3 mrad or less.

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that partial wedgeangle A_(y) be the largest among the three partial wedge angles of thepartial wedge angle A_(y), partial wedge angle B_(y), and partial wedgeangle C_(y).

From the viewpoint of effectively suppressing double images, especiallyfrom the viewpoint of effectively suppressing double images regardlessof the seated height of the observer, it is preferred that partial wedgeangle C_(y) be the smallest among the three partial wedge angles of thepartial wedge angle A_(y), partial wedge angle B_(y), and partial wedgeangle C_(y).

From the viewpoint of suppressing double images more effectively,especially from the viewpoint of suppressing double images regardless ofthe seated height of the observer more effectively, it is preferred thatthe partial wedge angle A_(y) be the largest and the partial wedge angleC_(y) be the smallest among the three partial wedge angles of thepartial wedge angle A_(y), partial wedge angle B_(y), and partial wedgeangle C_(y).

As a method for controlling difference between partial wedge angle A_(x)and partial wedge angle φ_(x), difference between partial wedge angleB_(x) and partial wedge angle (ex, difference between partial wedgeangle C_(x) and partial wedge angle φ_(x), difference between partialwedge angle A_(y) and partial wedge angle φ_(y), difference betweenpartial wedge angle B_(y) and partial wedge angle φ_(y), and differencebetween partial wedge angle C_(y) and partial wedge angle φ_(y), thefollowing methods and the like can be recited. A method of adjusting thelip gap of the lip die within a certain range at the time of extrusionmolding of the interlayer film, a method of adjusting the thickness bycontrolling the die temperature, and a method of adjusting the thicknessby adjusting the pick-up speed of the interlayer film discharged fromthe lip die.

In order to suppress double images, the wedge angle θ of the interlayerfilm can be appropriately set according to the fitting angle oflaminated glass. The wedge angle θ is a wedge angle of the interlayerfilm as a whole.

The wedge angle θ of the interlayer film is an interior angle formed atthe intersection point between a straight line connecting surface partson the one side of the interlayer film (first surface part) of themaximum thickness part and the minimum thickness part in the interlayerfilm, and a straight line connecting surface parts of the other side ofthe interlayer film (second surface part) of the maximum thickness partand the minimum thickness part in the interlayer film.

When there are a plurality of maximum thickness parts, there are aplurality of minimum thickness parts, the maximum thickness part islocated in a certain region, or the minimum thickness part is located ina certain region, the maximum thickness part and the minimum thicknesspart for determining the wedge angle θ are selected so that the wedgeangle θ to be determined is the maximum.

From the viewpoint of suppressing double images more effectively, thewedge angle θ of the interlayer film is preferably 0.05 mrad or more,more preferably 0.1 mrad (0.00575 degrees) or more, further preferably0.2 mrad (0.0115 degrees) or more. When the wedge angle θ is the abovelower limit or more, it is possible to obtain laminated glass suited forcars such as a truck or a bus in which the attachment angle of thewindshield is large.

From the viewpoint of suppressing double images more effectively, thewedge angle θ of the interlayer film is preferably 2 mrad (0.1146degrees) or less, and more preferably 0.7 mrad (0.0401 degrees) or less.When the wedge angle θ is the above upper limit or less, it is possibleto obtain laminated glass suited for cars such as a sports car in whichthe attachment angle of the windshield is small.

In the interlayer film according to the present invention, and theinterlayer film in the laminated glass according to the presentinvention, when partial wedge angle T in the following region A ismeasured, it is preferred that difference between the maximum value andthe minimum value of partial wedge angle Ψ be 0.15 mrad or less.

Partial wedge angle Ψ is measured in the order of the following 1 to 2.

1: Define region A starting at a position of 20 cm from the one endtoward the other end of the interlayer film and ending at a position of59.5 cm from the one end toward the other end of the interlayer film,and select points A at 2-mm intervals.

2: Calculate partial wedge angle Ψ of the interlayer film in eachpartial region Ψ of 80 mm centered at each of the points A in thedirection connecting the one end and the other end.

In the above step 1, points are selected up to the position whereselection of points at 2-mm intervals can be made from the one end sidetoward the other end side (positions of which interval is not less than2 mm).

In the above “2:”, the partial region Ψ closest to the one end side ofthe interlayer film is a partial region Ψ1 of 16 cm to 24 cm from theone end, and the next partial region Ψ is a partial region Ψ2 of 16.2 cmto 24.2 cm from the one end. Neighboring two partial regions Ψ overlapwith each other by 78 mm in the direction connecting the one end and theother end. Each partial region Ψ is a partial region of (16+0.2×n) cm to(24+0.2×n) cm from the one end (n is an integer).

In the above “2:”, a partial wedge angle calculated at each partialregion Ψ is referred to as partial wedge angle (θΨ).

One partial wedge angle (θΨ) is a wedge angle determined from anapproximation curve of the variation in thickness from the end part ofone end side toward the end part of the other end side in one partialregion A.

The maximum value of partial wedge angles Ψ is the largest value amongall the partial wedge angles Ψ measured in each partial region Ψ. Theminimum value of partial wedge angles Ψ is the smallest value among allthe partial wedge angles Ψ measured in each partial region Ψ.

It is preferred that the thickness increase from the one end toward theother end of the interlayer film in a region of 80% or more (morepreferably 85% or more, further preferably 90% or more, especiallypreferably 95% or more) of the region between a position of 6 cm fromthe one end toward the other end of the interlayer film and a positionof 63.8 cm from the one end toward the other end. In this case, it ispossible to suppress double images more effectively.

It is preferred that the thickness increase from the one end toward theother end of the interlayer film in a region of 80% or more (morepreferably 85% or more, further preferably 90% or more, especiallypreferably 95% or more) of the region between a position of 8 cm fromthe one end toward the other end of the interlayer film and a positionof 61.8 cm from the one end toward the other end. In this case, it ispossible to suppress double images more effectively.

It is preferred that the thickness increase from the one end toward theother end of the interlayer film in a region of 80% or more (morepreferably 85% or more, further preferably 90% or more, especiallypreferably 95% or more) of the region between a position of 9 cm fromthe one end toward the other end of the interlayer film and a positionof 60.8 cm from the one end toward the other end. In this case, it ispossible to suppress double images more effectively.

It is preferred that the thickness increase from the one end toward theother end of the interlayer film in a region of 80% or more (morepreferably 85% or more, further preferably 90% or more, especiallypreferably 95% or more) of the region between a position of 9.5 cm fromthe one end toward the other end of the interlayer film and a positionof 60.3 cm from the one end toward the other end. In this case, it ispossible to suppress double images more effectively.

It is more preferred that the thickness increase from the one end towardthe other end of the interlayer film in a region of 80% or more (morepreferably 85% or more, further preferably 90% or more, especiallypreferably 95% or more) of the region between a position of 10 cm fromthe one end toward the other end of the interlayer film and a positionof 59.8 cm from the one end toward the other end. In this case, it ispossible to suppress double images more effectively.

The interlayer film according to the present invention is suitably usedfor laminated glass that is a head-up display (HUD). It is preferredthat the interlayer film according to the present invention be aninterlayer film for HUD.

It is preferred that the laminated glass according to the presentinvention be a head-up display (HUD).

A head-up display system can be obtained by using the aforementionedhead-up display. The head-up display system includes the laminatedglass, and a light source device for irradiating the laminated glasswith light for image display. The light source device can be attached,for example, to a dashboard in a vehicle. By irradiating the displayregion of the laminated glass with light from the light source device,it is possible to achieve image display.

It is preferred that the interlayer film according to the presentinvention have a region for display corresponding to a display region ofHUD.

From the viewpoint of suppressing double images more effectively, it ispreferred that the interlayer film have the region for display in aregion between a position of 6 cm from the one end toward the other endof the interlayer film and a position of 63.8 cm from the one end towardthe other end.

From the viewpoint of suppressing double images more effectively, it ispreferred that the interlayer film have the region for display in aregion between a position of 8 cm from the one end toward the other endof the interlayer film and a position of 61.8 cm from the one end towardthe other end.

From the viewpoint of suppressing double images more effectively, it ispreferred that the interlayer film have the region for display in aregion between a position of 9 cm from the one end toward the other endof the interlayer film and a position of 60.8 cm from the one end towardthe other end.

From the viewpoint of suppressing double images more effectively, it ispreferred that the interlayer film have the region for display in aregion between a position of 9.5 cm from the one end toward the otherend of the interlayer film and a position of 60.3 cm from the one endtoward the other end.

From the viewpoint of suppressing double images more effectively, it ismore preferred that the interlayer film have the region for display in aregion between a position of 10 cm from the one end toward the other endof the interlayer film and a position of 59.8 cm from the one end towardthe other end.

The region for display may exist in a part or the whole of the region upto the aforementioned position (for example, 63.8 mm) from the one endtoward the other end of the interlayer film. The region for display mayexist in a size of about 30 cm in the direction connecting the one endand the other end.

From the viewpoint of suppressing double images effectively, it ispreferred that the interlayer film have a portion with a sectional shapein the thickness direction of a wedge-like shape in the region between aposition of 6 cm from the one end toward the other end of the interlayerfilm and a position of 63.8 cm from the one end toward the other end.

From the viewpoint of suppressing double images effectively, it ispreferred that the interlayer film have a portion with a sectional shapein the thickness direction of a wedge-like shape in the region between aposition of 8 cm from the one end toward the other end of the interlayerfilm and a position of 61.8 cm from the one end toward the other end.

From the viewpoint of suppressing double images effectively, it ispreferred that the interlayer film have a portion with a sectional shapein the thickness direction of a wedge-like shape in the region between aposition of 9 cm from the one end toward the other end of the interlayerfilm and a position of 60.8 cm from the one end toward the other end.

From the viewpoint of suppressing double images effectively, it ispreferred that the interlayer film have a portion with a sectional shapein the thickness direction of a wedge-like shape in the region between aposition of 9.5 cm from the one end toward the other end of theinterlayer film and a position of 60.3 cm from the one end toward theother end.

From the viewpoint of suppressing double images effectively, it is morepreferred that the interlayer film have a portion with a sectional shapein the thickness direction of a wedge-like shape in the region between aposition of 10 cm from the one end toward the other end of theinterlayer film and a position of 59.8 cm from the one end toward theother end.

The portion with a sectional shape in the thickness direction of awedge-like shape may exist in a part or the whole of the region up tothe aforementioned position (for example, 63.8 mm) from the one endtoward the other end. The portion with a sectional shape in thethickness direction of a wedge-like shape may exist in a size of about30 cm in the direction connecting the one end and the other end.

The interlayer film according to the present invention may have ashading region. The shading region may be separate from the region fordisplay. The shading region is provided so as to prevent a driver fromfeeling glare while driving, for example, by sunlight or outdoorlighting. The shading region can be provided so as to impart the heatblocking property. It is preferred that the shading region be located inan edge portion of the interlayer film. It is preferred that the shadingregion be belt-shaped.

In the shading region, a coloring agent or a filler may be used so as tochange the color and the visible light transmittance. The coloring agentor the filler may be contained in a partial region in the thicknessdirection of the interlayer film or may be contained in the entireregion in the thickness direction of the interlayer film.

From the viewpoint of providing better display, and further broadeningthe field of view, the visible light transmittance of the region fordisplay is preferably 80% or more, more preferably 88% or more, furtherpreferably 90% or more. It is preferred that the visible lighttransmittance of the region for display be higher than the visible lighttransmittance of the shading region. The visible light transmittance ofthe region for display may be lower than the visible light transmittanceof the shading region. The visible light transmittance of the region fordisplay is higher than the visible light transmittance of the shadingregion preferably by 50% or more, more preferably by 60% or more.

When the visible light transmittance varies in the interlayer film ofeach of the region for display and the shading region, the visible lighttransmittance is measured at the center position of the region fordisplay and at the center position of the shading region.

The visible light transmittance at a wavelength ranging from 380 nm to780 nm of the obtained laminated glass can be measured by using aspectrophotometer (“U-4100” available from Hitachi High-TechCorporation) in conformity with JIS R3211:1998. As the glass plate, itis preferred to use clear glass having a thickness of 2 mm.

It is preferred that the region for display have a length direction anda width direction. For excellent versatility of the interlayer film, itis preferred that the width direction of the region for display be thedirection connecting the one end and the other end. It is preferred thatthe region for display be belt-shaped.

It is preferred that the interlayer film has an MD direction and a TDdirection. For example, the interlayer film is obtained by meltextrusion molding. The MD direction is a flow direction of an interlayerfilm at the time of producing the interlayer film. The TD direction is adirection orthogonal to the flow direction of an interlayer film at thetime of producing the interlayer film and a direction orthogonal to thethickness direction of the interlayer film. It is preferred that the oneend and the other end be located on either side of the TD direction.

From the viewpoint of better display, it is preferred that theinterlayer film have a portion with a sectional shape in the thicknessdirection of a wedge-like shape. It is preferred that the sectionalshape in the thickness direction of the region for display be awedge-like shape.

Hereinafter, specific embodiments of the present invention will bedescribed with reference to the drawings.

FIGS. 1(a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass inaccordance with a first embodiment of the present invention. FIG. 1(a)is a sectional view along the line I-I in FIG. 1(b). The size anddimension of the interlayer film in FIG. 1 and later described drawingsare appropriately changed from the actual size and shape for convenienceof illustration.

In FIG. 1(a), a section in the thickness direction of an interlayer film11 is shown. In this connection, in FIG. 1(a) and later describeddrawings, for convenience of illustration, the thicknesses of aninterlayer film and respective layers constituting the interlayer filmand the wedge angle (θ) are shown so as to be different from actualthicknesses thereof and an actual wedge angle.

The interlayer film 11 is provided with a first layer 1 (intermediatelayer), a second layer 2 (surface layer), and a third layer 3 (surfacelayer). The second layer 2 is arranged on a first surface side of thefirst layer 1 to be layered thereon. The third layer 3 is arranged on asecond surface side opposite to the first surface of the first layer 1to be layered thereon. The first layer 1 is arranged between the secondlayer 2 and the third layer 3 to be sandwiched therebetween. Theinterlayer film 11 is used for obtaining laminated glass. The interlayerfilm 11 is an interlayer film for laminated glass. The interlayer film11 is a multilayer interlayer film.

The interlayer film 11 has one end 11 a and the other end 11 b at theopposite side of the one end 11 a. The one end 11 a and the other end 11b are end parts of both sides facing each other. The sectional shape inthe thickness direction of each of the second layer 2 and the thirdlayer 3 is a wedge-like shape. The sectional shape in the thicknessdirection of the first layer 1 is a rectangular shape. The thicknessesof the second layer 2 and the third layer 3 are larger in the other end11 b side than in the one end 11 a side. Accordingly, the thickness ofthe other end 11 b of the interlayer film 11 is larger than thethickness of the one end 11 a thereof. Accordingly, the interlayer film11 has a region being thin in thickness and a region being thick inthickness.

The interlayer film 11 has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. In the interlayer film11, the increment of the thickness is constant from the one end 11 aside to the other end 11 b side in the region where the thicknessincreases.

The interlayer film 11 has a region for display R1 corresponding to adisplay region of a head-up display. The region for display R1 has afirst partial region for display R11, a second partial region fordisplay R12, and a third partial region for display R13. The firstpartial region for display R11, the second partial region for displayR12, and the third partial region for display R13 are three regionsobtained by equally dividing the region for display R1 into three in thedirection connecting the one end 11 a and the other end 11 b. In theregion for display R1, the first partial region for display R11 islocated on the one end 11 a side. In the region for display R1, thesecond partial region for display R12 is located between the firstpartial region for display R11 and the third partial region for displayR13. In the region for display R1, the third partial region for displayR13 is located on the other end 11 b side.

In the present embodiment, the region for display R1 is a region betweena position of 10 cm from the one end 11 a toward the other end 11 b anda position of 59.5 cm from the one end 11 a toward the other end 11 b.In the present embodiment, the first partial region for display R11 is aregion between a position of 10 cm from the one end 11 a toward theother end 11 b and a position of 26.5 cm from the one end 11 a towardthe other end 11 b. In the present embodiment, the second partial regionfor display R12 is a region between a position of 26.5 cm from the oneend 11 a toward the other end 11 b and a position of 43 cm from the oneend 11 a toward the other end 11 b. In the present embodiment, the thirdpartial region for display R13 is a region between a position of 43 cmfrom the one end 11 a toward the other end 11 b and a position of 59.5cm from the one end 11 a toward the other end 11 b.

The interlayer film 11 has a surrounding region R2 neighboring theregion for display R1.

The interlayer film 11 has a shading region R3 that is separate from theregion for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11.

The interlayer film has a shape as shown in FIG. 1(a), and may have aone-layer structure, a two-layer structure or four or more-layerstructure.

FIG. 8 is a perspective view schematically showing a roll body preparedby winding the interlayer film for laminated glass shown in FIG. 1 .

An interlayer film 11 may be wound to be formed into a roll body 51 ofthe interlayer film 11.

The roll body 51 shown in FIG. 8 includes a winding core 61 and theinterlayer film 11. The interlayer film 11 is wound around an outerperiphery of the winding core 61.

FIGS. 2 (a) and (b) are a sectional view and a front view, respectively,schematically showing an interlayer film for laminated glass inaccordance with a second embodiment of the present invention. FIG. 2(a)is a sectional view along the line I-I in FIG. 2(b). In FIG. 2(a), asection in the thickness direction of an interlayer film 11A is shown.

The interlayer film 11A shown in FIG. 2 is provided with a first layer1A. The interlayer film 11A has a one-layer structure composed only ofthe first layer 1A and is a single-layered interlayer film. Theinterlayer film 11A is singly constituted by the first layer 1A. Theinterlayer film 11A is used for obtaining laminated glass. Theinterlayer film 11A is an interlayer film for laminated glass.

The interlayer film 11A has one end 11 a and the other end 11 b at theopposite side of the one end 11 a. The one end 11 a and the other end 11b are end parts of both sides facing each other. The thickness of theother end 11 b of the interlayer film 11A is larger than the thicknessof the one end 11 a thereof. Accordingly, the first layer 1Acorresponding to the interlayer film 11A has a region being thin inthickness and a region being thick in thickness.

The interlayer film 11A has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. In the interlayer film11A, the increment of the thickness is constant from the one end 11 aside to the other end 11 b side in the region where the thicknessincreases.

The interlayer film 11A and the first layer 1A have portions 11Aa, 1Aahaving a rectangular sectional shape in the thickness direction, andportions 11Ab, 1Ab having a wedge-like sectional shape in the thicknessdirection.

The interlayer film 11A has a region for display R1 corresponding to adisplay region of a head-up display. The region for display R1 has afirst partial region for display R11, a second partial region fordisplay R12, and a third partial region for display R13. The firstpartial region for display R11, the second partial region for displayR12, and the third partial region for display R13 are three regionsobtained by equally dividing the region for display R1 into three in thedirection connecting the one end 11 a and the other end 11 b. In theregion for display R1, the first partial region for display R11 islocated on the one end 11 a side. In the region for display R1, thesecond partial region for display R12 is located between the firstpartial region for display R11 and the third partial region for displayR13. In the region for display R1, the third partial region for displayR13 is located on the other end 11 b side.

The interlayer film 11A has a surrounding region R2 neighboring theregion for display R1.

The interlayer film 11A has a shading region R3 that is separate fromthe region for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11A.

The interlayer film has a shape as shown in FIG. 2(a) and may have a twoor more layer structure.

FIG. 3 is a sectional view schematically showing an interlayer film forlaminated glass in accordance with a third embodiment of the presentinvention. In FIG. 3 , a section in the thickness direction of aninterlayer film 11B is shown.

The interlayer film 11B shown in FIG. 3 includes a first layer 1B(intermediate layer), a second layer 2B (surface layer), and a thirdlayer 3B (surface layer). The interlayer film 11 and the interlayer film11B are different from each other in the increment of the thickness inthe region where the thickness increases.

The interlayer film 11B has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. The interlayer film11B has a portion where the increment of the thickness increases fromthe one end 11 a side to the other end 11 b side in the region where thethickness increases. The interlayer film 11B has a region with asectional shape in the thickness direction of a wedge-like shape. Theinterlayer film 11B has a portion where the wedge angle increases fromthe one end side to the other end side in the region with a sectionalshape in the thickness direction of a wedge-like shape.

The interlayer film 11B has a region for display R1 corresponding to adisplay region of a head-up display. The region for display R1 has afirst partial region for display R11, a second partial region fordisplay R12, and a third partial region for display R13. The firstpartial region for display R11, the second partial region for displayR12, and the third partial region for display R13 are three regionsobtained by equally dividing the region for display R1 into three in thedirection connecting the one end 11 a and the other end 11 b. In theregion for display R1, the first partial region for display R11 islocated on the one end 11 a side. In the region for display R1, thesecond partial region for display R12 is located between the firstpartial region for display R11 and the third partial region for displayR13. In the region for display R1, the third partial region for displayR13 is located on the other end 11 b side.

The region for display R1 has a region where the thickness increasesfrom the one end 11 a side to the other end 11 b side. The region fordisplay R1 may have a portion where the increment of the thicknessvaries from the one end 11 a side to the other end 11 b side in theregion where the thickness increases. The region for display R1 has aregion with a sectional shape in the thickness direction of a wedge-likeshape. The region for display R1 may have a portion where the wedgeangle varies from the one end side to the other end side in the regionwith a sectional shape in the thickness direction of a wedge-like shape.

The interlayer film 11B has a surrounding region R2 neighboring theregion for display R1.

The interlayer film 11B has a shading region R3 that is separate fromthe region for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11B.

FIG. 4 is a sectional view schematically showing an interlayer film forlaminated glass in accordance with a fourth embodiment of the presentinvention. In FIG. 4 , a section in the thickness direction of aninterlayer film 11C is shown.

The interlayer film 11C shown in FIG. 4 includes a first layer 1C. Theinterlayer film 11C has a one-layer structure composed only of the firstlayer 1C and is a single-layered interlayer film. The interlayer film11A and the interlayer film 11C are different from each other in theincrement of the thickness in the region where the thickness increases.

The interlayer film 11C has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. The interlayer film11C has a portion where the increment of the thickness increases fromthe one end 11 a side to the other end 11 b side in the region where thethickness increases. The interlayer film 11C has a region with asectional shape in the thickness direction of a wedge-like shape. Theinterlayer film 11C has a portion where the wedge angle increases fromthe one end side to the other end side in the region with a sectionalshape in the thickness direction of a wedge-like shape.

The interlayer film 11C and the first layer 1C have portions 11Ca, 1Cahaving a rectangular sectional shape in the thickness direction, andportions 11Cb, 1Cb having a wedge-like sectional shape in the thicknessdirection.

The interlayer film 11C has a region for display R1 corresponding to adisplay region of a head-up display. The region for display R1 has afirst partial region for display R11, a second partial region fordisplay R12, and a third partial region for display R13. The firstpartial region for display R11, the second partial region for displayR12, and the third partial region for display R13 are three regionsobtained by equally dividing the region for display R1 into three in thedirection connecting the one end 11 a and the other end 11 b. In theregion for display R1, the first partial region for display R11 islocated on the one end 11 a side. In the region for display R1, thesecond partial region for display R12 is located between the firstpartial region for display R11 and the third partial region for displayR13. In the region for display R1, the third partial region for displayR13 is located on the other end lib side.

The region for display R1 has a region where the thickness increasesfrom the one end 11 a side to the other end 11 b side. The region fordisplay R1 may have a portion where the increment of the thicknessvaries from the one end 11 a side to the other end 11 b side in theregion where the thickness increases. The region for display R1 has aregion with a sectional shape in the thickness direction of a wedge-likeshape. The region for display R1 may have a portion where the wedgeangle varies from the one end side to the other end side in the regionwith a sectional shape in the thickness direction of a wedge-like shape.

The interlayer film 11C has a surrounding region R2 neighboring theregion for display R1.

The interlayer film 11C has a shading region R3 that is separate fromthe region for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11C.

FIG. 5 is a sectional view schematically showing an interlayer film forlaminated glass in accordance with a fifth embodiment of the presentinvention. In FIG. 5 , a section in the thickness direction of aninterlayer film 11D is shown.

The interlayer film 11D shown in FIG. 5 includes a first layer 1D(intermediate layer), a second layer 2D (surface layer), and a thirdlayer 3D (surface layer). The interlayer film 11 and the interlayer film11D are different from each other in the increment of the thickness inthe region where the thickness increases.

The interlayer film 11D has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. The interlayer film11D has a portion where the increment of the thickness decreases fromthe one end 11 a side to the other end lib side in the region where thethickness increases. The interlayer film 11D has a region with asectional shape in the thickness direction of a wedge-like shape. Theinterlayer film 11D has a portion where the wedge angle decreases fromthe one end side to the other end side in the region with a sectionalshape in the thickness direction of a wedge-like shape.

The interlayer film 11D has a region for display R1 corresponding to adisplay region of a head-up display. The region for display R1 has afirst partial region for display R11, a second partial region fordisplay R12, and a third partial region for display R13. The firstpartial region for display R11, the second partial region for displayR12, and the third partial region for display R13 are three regionsobtained by equally dividing the region for display R1 into three in thedirection connecting the one end 11 a and the other end 11 b. In theregion for display R1, the first partial region for display R11 islocated on the one end 11 a side. In the region for display R1, thesecond partial region for display R12 is located between the firstpartial region for display R11 and the third partial region for displayR13. In the region for display R1, the third partial region for displayR13 is located on the other end 11 b side.

The region for display R1 has a region where the thickness increasesfrom the one end 11 a side to the other end 11 b side. The region fordisplay R1 may have a portion where the increment of the thicknessvaries from the one end 11 a side to the other end 11 b side in theregion where the thickness increases. The region for display R1 has aregion with a sectional shape in the thickness direction of a wedge-likeshape. The region for display R1 may have a portion where the wedgeangle varies from the one end side to the other end side in the regionwith a sectional shape in the thickness direction of a wedge-like shape.

The interlayer film 11D has a surrounding region R2 neighboring theregion for display R1.

The interlayer film 11D has a shading region R3 that is separate fromthe region for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11D.

FIG. 6 is a sectional view schematically showing an 1C interlayer filmfor laminated glass in accordance with a sixth embodiment of the presentinvention. In FIG. 6 , a section in the thickness direction of aninterlayer film 11E is shown.

The interlayer film 11E shown in FIG. 6 includes a first layer 1E. Theinterlayer film 11E has a one-layer structure composed only of the firstlayer 1E and is a single-layered interlayer film. The interlayer film11A and the interlayer film 11E are different from each other in theincrement of the thickness in the region where the thickness increases.

The interlayer film 11E has a region where the thickness increases fromthe one end 11 a side to the other end 11 b side. The interlayer film11E may have a portion where the increment of the thickness varies fromthe one end 11 a side to the other end 11 b side in the region where thethickness increases. The interlayer film 11E has a region with asectional shape in the thickness direction of a wedge-like shape. Theinterlayer film 11E may have a portion where the wedge angle varies fromthe one end side to the other end side in the region with a sectionalshape in the thickness direction of a wedge-like shape.

The interlayer film 11E and the first layer 1E have portions 11Ea, 1Eahaving a rectangular sectional shape in the thickness direction, andportions 11Eb, 1Eb having a wedge-like sectional shape in the thicknessdirection.

The interlayer film 11E has a region for display R1 corresponding to adisplay region of a head-up display. The region for display R1 has afirst partial region for display R11, a second partial region fordisplay R12, and a third partial region for display R13. The firstpartial region for display R11, the second partial region for displayR12, and the third partial region for display R13 are three regionsobtained by equally dividing the region for display R1 into three in thedirection connecting the one end 11 a and the other end 11 b. In theregion for display R1, the first partial region for display R11 islocated on the one end 11 a side. In the region for display R1, thesecond partial region for display R12 is located between the firstpartial region for display R11 and the third partial region for displayR13. In the region for display R1, the third partial region for displayR13 is located on the other end 11 b side.

The region for display R1 has a region where the thickness increasesfrom the one end 11 a side to the other end 11 b side. The region fordisplay R1 may have a portion where the increment of the thicknessvaries from the one end 11 a side to the other end 11 b side in theregion where the thickness increases. The region for display R1 has aregion with a sectional shape in the thickness direction of a wedge-likeshape. The region for display R1 may have a portion where the wedgeangle varies from the one end side to the other end side in the regionwith a sectional shape in the thickness direction of a wedge-like shape.

The interlayer film 11E has a surrounding region R2 neighboring theregion for display R1.

The interlayer film 11E has a shading region R3 that is separate fromthe region for display R1. The shading region R3 is located in an edgeportion of the interlayer film 11E.

It is preferred that the interlayer film have a portion with a sectionalshape in the thickness direction of a wedge-like shape. It is preferredthat the interlayer film have a portion where the thickness graduallyincreases from one end toward the other end. It is preferred that thesectional shape in the thickness direction of the interlayer film be awedge-like shape. Examples of the sectional shape in the thicknessdirection of the interlayer film include a trapezoidal shape, atriangular shape, a pentagonal shape, and the like.

In the above-described interlayer film, the thickness may not increaseevenly from the one end toward the other end of the interlayer film. Theabove-described interlayer film may have a projecting portion on thesurface, or a recess portion on the surface.

From the viewpoint of further suppressing double images, it is preferredthat the interlayer film have a portion where the increment of thethickness increases from the one end side to the other end side in theregion where the thickness increases. From the viewpoint of furthersuppressing double images, it is preferred that the interlayer film havea portion where the wedge angle increases from the one end side to theother end side in the region where the sectional shape in the thicknessdirection is a wedge-like shape.

The thickness of the interlayer film is not particularly limited. Thethickness of the interlayer film refers to the total thickness of therespective layers constituting the interlayer film. Thus, in the case ofa multi-layered interlayer film 11, the thickness of the interlayer filmrefers to the total thickness of the first layer 1, the second layer 2,and the third layer 3.

The maximum thickness of the interlayer film is preferably 0.1 mm ormore, more preferably 0.25 mm or more, further preferably 0.5 mm ormore, especially preferably 0.8 mm or more and is preferably 3 mm orless, more preferably 2 mm or less, further preferably 1.5 mm or less.

A distance between one end and the other end of the interlayer film isdefined as X. It is preferred that the interlayer film have a minimumthickness in the region at a distance of 0X to 0.2X inwardly from theone end, and a maximum thickness in the region at a distance of 0X to0.2X inwardly from the other end. It is more preferred that theinterlayer film have a minimum thickness in the region at a distance of0X to 0.1X inwardly from the one end, and a maximum thickness in theregion at a distance of 0X to 0.1X inwardly from the other end. It ispreferred that the interlayer film have a minimum thickness at the oneend and the interlayer film have a maximum thickness at the other end.

The interlayer films 11, 11A, 11B, 11C, 11D, 11E have a maximumthickness in the other end 11 b and a minimum thickness in the one end11 a.

The interlayer film may have a uniform-thickness part. Theuniform-thickness part means that the variation in thickness does notexceed 10 μm per a distance range of 10 cm in the direction connectingthe one end and the other end of the interlayer film. Therefore, theuniform-thickness part refers to the part where the variation inthickness does not exceed 10 μm per a distance range of 10 cm in thedirection connecting the one end and the other end of the interlayerfilm. To be more specific, the uniform-thickness part refers to the partwhere the thickness does not vary at all in the direction connecting theone end and the other end of the interlayer film, or the thicknessvaries by 10 μm or less per a distance range of 10 cm in the directionconnecting the one end and the other end of the interlayer film.

From the viewpoint of the practical aspect and the viewpoint ofsufficiently enhancing the adhesive force and the penetrationresistance, the maximum thickness of a surface layer in the interlayerfilm is preferably 0.001 mm or more, more preferably 0.2 mm or more,further preferably 0.3 mm or more, and is preferably 1 mm or less, andmore preferably 0.8 mm or less.

From the viewpoint of the practical aspect and the viewpoint ofsufficiently enhancing the penetration resistance, the maximum thicknessof a layer (intermediate layer) arranged between two surface layers inthe interlayer film is preferably 0.001 mm or more, more preferably 0.1mm or more, and further preferably 0.2 mm or more and is preferably 0.8mm or less, more preferably 0.6 mm or less, and further preferably 0.3mm or less.

The distance X between one end and the other end of the interlayer filmis preferably 3 m or less, more preferably 2 m or less, especiallypreferably 1.5 m or less, and preferably 0.5 m or more, more preferably0.8 m or more, and especially preferably 1 m or more.

As a measuring device for use for measurement of a partial wedge angleof the interlayer film, a wedge angle (θ) of the interlayer film, and athickness of the interlayer film, a contact type thickness measuringinstrument “TOF-4R” (available from Yamabun Electronics Co., Ltd.) orthe like can be recited.

Measurement of the thickness is conducted so that the distance is theshortest from the one end toward the other end by using theabove-described measuring device at a film conveyance speed of 2.15mm/minute to 2.25 mm/minute.

As a measuring device for use for measurement of a partial wedge angleof the interlayer film, a wedge angle (θ) of the interlayer film, and athickness of the interlayer film after the interlayer film is made intolaminated glass, a non-contact type multilayer film thickness measuringinstrument “OPTIGAUGE” (available from Lumetrics, Inc.) or the like canbe recited. The thickness of the interlayer film can be measured whilethe interlayer film is in the laminated glass.

Hereinafter, the details of materials constituting the respective layersof a multi-layered interlayer film and the single-layered interlayerfilm will be described.

(Resin)

It is preferred that the interlayer film contain a resin. One kind ofthe resin may be used alone, and two or more kinds thereof may be usedin combination.

Examples of the resin include thermosetting resins and thermoplasticresins.

It is preferred that the interlayer film contain a resin (hereinafter,sometimes described as a resin (0)). It is preferred that the interlayerfilm contain a thermoplastic resin (hereinafter, sometimes described asa thermoplastic resin (0)). It is preferred that the interlayer filmcontain a polyvinyl acetal resin (hereinafter, sometimes described as apolyvinyl acetal resin (0)) as the thermoplastic resin (0). It ispreferred that the first layer contain a resin (hereinafter, sometimesdescribed as a resin (1)). It is preferred that the first layer containa thermoplastic resin (hereinafter, sometimes described as athermoplastic resin (1)). It is preferred that the first layer contain apolyvinyl acetal resin (hereinafter, sometimes described as a polyvinylacetal resin (1)) as the thermoplastic resin (1). It is preferred thatthe second layer contain a resin (hereinafter, sometimes described as aresin (2)). It is preferred that the second layer contain athermoplastic resin (hereinafter, sometimes described as a thermoplasticresin (2)). It is preferred that the second layer contain a polyvinylacetal resin (hereinafter, sometimes described as a polyvinyl acetalresin (2)) as the thermoplastic resin (2). It is preferred that thethird layer contain a resin (hereinafter, sometimes described as a resin(3)). It is preferred that the third layer contain a thermoplastic resin(hereinafter, sometimes described as a thermoplastic resin (3)). It ispreferred that the third layer contain a polyvinyl acetal resin(hereinafter, sometimes described as a polyvinyl acetal resin (3)) asthe thermoplastic resin (3). The resin (1), the resin (2), and the resin(3) may be the same as or different from one another. For still highersound insulating properties, it is preferred that the resin (1) bedifferent from the resin (2) and the resin (3). The thermoplastic resin(1), the thermoplastic resin (2), and the thermoplastic resin (3) may bethe same or different from one another. For still higher soundinsulating properties, it is preferred that the thermoplastic resin (1)be different from the thermoplastic resin (2) and the thermoplasticresin (3). Each of the polyvinyl acetal resin (1), the polyvinyl acetalresin (2) and the polyvinyl acetal resin (3) may be the same ordifferent from one another. For still higher sound insulatingproperties, it is preferred that the polyvinyl acetal resin (1) bedifferent from the polyvinyl acetal resin (2) and the polyvinyl acetalresin (3). One kind of each of the thermoplastic resin (0), thethermoplastic resin (1), the thermoplastic resin (2), and thethermoplastic resin (3) may be used alone and two or more kinds thereofmay be used in combination. One kind of each of the polyvinyl acetalresin (0), the polyvinyl acetal resin (1), the polyvinyl acetal resin(2), and the polyvinyl acetal resin (3) may be used alone and two ormore kinds thereof may be used in combination.

Examples of the thermoplastic resin include a polyvinyl acetal resin, apolyester resin, an ethylene-vinyl acetate copolymer resin, anethylene-acrylic acid copolymer resin, a polyurethane resin, a polyvinylalcohol resin, and the like. Thermoplastic resins other than these maybe used. The polyoxymethylene (or polyacetal) resin is included in thepolyvinyl acetal resin.

It is preferred that the resin be a thermoplastic resin. Thethermoplastic resin is more preferably a polyvinyl acetal resin or apolyester resin, and is further preferably a polyvinyl acetal resin. Byusing a polyvinyl acetal resin and a plasticizer together, the adhesiveforce of a layer containing the polyvinyl acetal resin and theplasticizer to a lamination glass member or another layer is furtherenhanced. It is preferred that the polyvinyl acetal resin be a polyvinylbutyral resin.

For example, the polyvinyl acetal resin can be produced by acetalizingpolyvinyl alcohol (PVA) with an aldehyde. It is preferred that thepolyvinyl acetal resin be an acetalized product of polyvinyl alcohol.For example, the polyvinyl alcohol can be obtained by saponifyingpolyvinyl acetate. The saponification degree of the polyvinyl alcoholgenerally lies within the range of 70% by mole to 99.9% by mole.

The average polymerization degree of the polyvinyl alcohol (PVA) ispreferably 200 or more, more preferably 500 or more, even morepreferably 1500 or more, further preferably 1600 or more, especiallypreferably 2600 or more, most preferably 2700 or more and is preferably5000 or less, more preferably 4000 or less, further preferably 3500 orless. When the average polymerization degree is the above lower limit ormore, the penetration resistance of laminated glass is further enhanced.When the average polymerization degree is the above upper limit or less,formation of an interlayer film is facilitated.

The average polymerization degree of the polyvinyl alcohol is determinedby a method in accordance with JIS K6726 “Testing methods for polyvinylalcohol”.

The number of carbon atoms of the acetal group contained in thepolyvinyl acetal resin is not particularly limited. The aldehyde used atthe time of producing the polyvinyl acetal resin is not particularlylimited. It is preferred that the number of carbon atoms of the acetalgroup in the polyvinyl acetal resin fall within the range of 3 to 5 andit is more preferred that the number of carbon atoms of the acetal groupbe 3 or 4. When the number of carbon atoms of the acetal group in thepolyvinyl acetal resin is 3 or more, the glass transition temperature ofthe interlayer film is sufficiently lowered. The number of carbon atomsof the acetal group in the polyvinyl acetal resin may be 4 or 5.

Aldehyde is not particularly limited. In general, an aldehyde with 1 to10 carbon atoms is preferably used. Examples of the aldehyde with 1 to10 carbon atoms include formaldehyde, acetaldehyde, propionaldehyde,n-butyraldehyde, isobutyraldehyde, n-valeraldehyde,2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde,n-decylaldehyde, and benzaldehyde. The aldehyde is preferablypropionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, orn-valeraldehyde, more preferably propionaldehyde, n-butyraldehyde, orisobutyraldehyde, and further preferably n-butyraldehyde. One kind ofthe aldehyde may be used alone, and two or more kinds thereof may beused in combination.

The content of the hydroxyl group (the amount of hydroxyl groups) of thepolyvinyl acetal resin (0) is preferably 15% by mole or more and morepreferably 18% by mole or more and is preferably 40% by mole or less andmore preferably 35% by mole or less. When the content of the hydroxylgroup is the above lower limit or more, the adhesive force of theinterlayer film is further enhanced. Moreover, when the content of thehydroxyl group is the above upper limit or less, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated.

The content of the hydroxyl group (hydroxyl group amount) of thepolyvinyl acetal resin (1) is preferably 17% by mole or more, morepreferably 20% by mole or more, and further preferably 22% by mole ormore. The content of the hydroxyl group (the amount of hydroxyl groups)of the polyvinyl acetal resin (1) is preferably 30% by mole or less,more preferably 28% by mole or less, still more preferably 27% by moleor less, further preferably 25% by mole or less, especially preferablyless than 25% by mole, most preferably 24% by mole or less. When thecontent of the hydroxyl group is the above lower limit or more, themechanical strength of the interlayer film is further enhanced. Inparticular, when the content of the hydroxyl group of the polyvinylacetal resin (1) is 20% by mole or more, the resin is high in reactionefficiency and is excellent in productivity, when being 28% by mole orless, the sound insulating properties of laminated glass are furtherenhanced, and when being 28% by mole or less, the sound insulatingproperties are further enhanced. Moreover, when the content of thehydroxyl group is the above upper limit or less, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated.

Each of the contents of the hydroxyl group of the polyvinyl acetal resin(2) and the polyvinyl acetal resin (3) is preferably 25% by mole ormore, more preferably 28% by mole or more, still more preferably 30% bymole or more, further preferably more than 31% by mole, still furtherpreferably 31.5% by mole or more, especially preferably 32% by mole ormore, and most preferably 33% by mole or more. Each of the contents ofthe hydroxyl group of the polyvinyl acetal resin (2) and the polyvinylacetal resin (3) is preferably 38% by mole or less, more preferably 37%by mole or less, further preferably 36.5% by mole or less, especiallypreferably 36% by mole or less. When the content of the hydroxyl groupis the above lower limit or more, the adhesive force of the interlayerfilm is further enhanced. Moreover, when the content of the hydroxylgroup is the above upper limit or less, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated.

From the viewpoint of further heightening the sound insulatingproperties, it is preferred that the content of the hydroxyl group ofthe polyvinyl acetal resin (1) be lower than the content of the hydroxylgroup of the polyvinyl acetal resin (2). From the viewpoint of furtherenhancing the sound insulating properties, it is preferred that thecontent of the hydroxyl group of the polyvinyl acetal resin (1) be lowerthan the content of the hydroxyl group of the polyvinyl acetal resin(3). From the viewpoint of still further enhancing the sound insulatingproperties, the absolute value of a difference between the content ofthe hydroxyl group of the polyvinyl acetal resin (1) and the content ofthe hydroxyl group of the polyvinyl acetal resin (2) is preferably 1% bymole or more, more preferably 5% by mole or more, further preferably 9%by mole or more, especially preferably 10% by mole or more, mostpreferably 12% by mole or more. From the viewpoint of still furtherenhancing the sound insulating properties, the absolute value of adifference between the content of the hydroxyl group of the polyvinylacetal resin (1) and the content of the hydroxyl group of the polyvinylacetal resin (3) is preferably 1% by mole or more, more preferably 5% bymole or more, further preferably 9% by mole or more, especiallypreferably 10% by mole or more, most preferably 12% by mole or more. Anabsolute value of difference between the content of the hydroxyl groupof the polyvinyl acetal resin (1) and the content of the hydroxyl groupof the polyvinyl acetal resin (2) is preferably 20% by mole or less. Anabsolute value of difference between the content of the hydroxyl groupof the polyvinyl acetal resin (1) and the content of the hydroxyl groupof the polyvinyl acetal resin (3) is preferably 20% by mole or less.

The content of the hydroxyl group of the polyvinyl acetal resin is amole fraction, represented in percentage, obtained by dividing theamount of ethylene groups to which the hydroxyl group is bonded by thetotal amount of ethylene groups in the main chain. For example, theamount of ethylene groups to which the hydroxyl group is bonded can bedetermined in conformity with JIS K6728 “Testing methods for polyvinylbutyral”.

The acetylation degree (the amount of acetyl groups) of the polyvinylacetal resin (0) is preferably 0.1% by mole or more, more preferably0.3% by mole or more, further preferably 0.5% by mole or more and ispreferably 30% by mole or less, more preferably 25% by mole or less,further preferably 20% by mole or less. When the acetylation degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetylation degreeis the above upper limit or less, with regard to the interlayer film andlaminated glass, the moisture resistance thereof is enhanced.

The acetylation degree (the amount of acetyl groups) of the polyvinylacetal resin (1) is preferably 0.01% by mole or more, more preferably0.1% by mole or more, even more preferably 7% by mole or more, furtherpreferably 9% by mole or more and is preferably 30% by mole or less,more preferably 25% by mole or less, further preferably 24% by mole orless, especially preferably 20% by mole or less. When the acetylationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetylation degree is the above upper limit or less, with regard to theinterlayer film and laminated glass, the moisture resistance thereof isenhanced. In particular, when the acetylation degree of the polyvinylacetal resin (1) is 0.1% by mole or more and is 25% by mole or less, theresulting laminated glass is excellent in penetration resistance.

The acetylation degree of each of the polyvinyl acetal resin (2) and thepolyvinyl acetal resin (3) is preferably 0.01% by mole or more and morepreferably 0.5% by mole or more and is preferably 10% by mole or lessand more preferably 2% by mole or less. When the acetylation degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetylation degreeis the above upper limit or less, with regard to the interlayer film andlaminated glass, the moisture resistance thereof is enhanced.

The acetylation degree is a mole fraction, represented in percentage,obtained by dividing the amount of ethylene groups to which the acetylgroup is bonded by the total amount of ethylene groups in the mainchain. For example, the amount of ethylene groups to which the acetylgroup is bonded can be determined in accordance with JIS K6728 “Testingmethods for polyvinyl butyral”.

The acetalization degree of the polyvinyl acetal resin (0) (thebutyralization degree in the case of a polyvinyl butyral resin) ispreferably 60% by mole or more and more preferably 63% by mole or moreand is preferably 85% by mole or less, more preferably 75% by mole orless, further preferably 70% by mole or less. When the acetalizationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetalization degree is the above upper limit or less, the reaction timerequired for producing the polyvinyl acetal resin is shortened.

The acetalization degree of the polyvinyl acetal resin (1) (thebutyralization degree in the case of a polyvinyl butyral resin) ispreferably 47% by mole or more and more preferably 60% by mole or moreand is preferably 85% by mole or less, more preferably 80% by mole orless, further preferably 75% by mole or less. When the acetalizationdegree is the above lower limit or more, the compatibility between thepolyvinyl acetal resin and a plasticizer is enhanced. When theacetalization degree is the above upper limit or less, the reaction timerequired for producing the polyvinyl acetal resin is shortened.

The acetalization degree of each of the polyvinyl acetal resin (2) andthe polyvinyl acetal resin (3) (the butyralization degree in the case ofa polyvinyl butyral resin) is preferably 55% by mole or more and morepreferably 60% by mole or more and is preferably 75% by mole or less andmore preferably 71% by mole or less. When the acetalization degree isthe above lower limit or more, the compatibility between the polyvinylacetal resin and a plasticizer is enhanced. When the acetalizationdegree is the above upper limit or less, the reaction time required forproducing the polyvinyl acetal resin is shortened.

The acetalization degree is determined in the following manner. From thetotal amount of the ethylene group in the main chain, the amount of theethylene group to which the hydroxyl group is bonded and the amount ofthe ethylene group to which the acetyl group is bonded are subtracted.The obtained value is divided by the total amount of the ethylene groupin the main chain to obtain a mole fraction. The mole fractionrepresented in percentage is the acetalization degree.

In this connection, it is preferred that the content of the hydroxylgroup (the amount of hydroxyl groups), the acetalization degree (thebutyralization degree) and the acetylation degree be calculated from theresults determined by a method in accordance with JIS K6728 “Testingmethods for polyvinyl butyral”. In this context, a method in accordancewith ASTM D1396-92 may be used. When the polyvinyl acetal resin is apolyvinyl butyral resin, the content of the hydroxyl group (the amountof hydroxyl groups), the acetalization degree (the butyralizationdegree) and the acetylation degree can be calculated from the resultsmeasured by a method in accordance with JIS K6728 “Testing methods forpolyvinyl butyral”.

In 100% by weight of the thermoplastic resin contained in the interlayerfilm, the content of the polyvinyl acetal resin is preferably 10% byweight or more, more preferably 30% by weight or more, still morepreferably 50% by weight or more, further preferably 70% by weight ormore, especially preferably 80% by weight or more, most preferably 90%by weight or more. It is preferred that the main ingredient (50% byweight or more) of the thermoplastic resin of the interlayer film be apolyvinyl acetal resin.

(Plasticizer)

From the viewpoint of further heightening the adhesive force of aninterlayer film, it is preferred that the interlayer film according tothe present invention contain a plasticizer (hereinafter, sometimesdescribed as a plasticizer (0)). It is preferred that the first layercontain a plasticizer (hereinafter, sometimes described as a plasticizer(1)). It is preferred that the second layer contain a plasticizer(hereinafter, sometimes described as a plasticizer (2)). It is preferredthat the third layer contain a plasticizer (hereinafter, sometimesdescribed as a plasticizer (3)). When the thermoplastic resin containedin the interlayer film is a polyvinyl acetal resin, it is especiallypreferred that the interlayer film (the respective layers) contain aplasticizer. It is preferred that a layer containing a polyvinyl acetalresin contain a plasticizer.

The plasticizer is not particularly limited. As the plasticizer, aconventionally known plasticizer can be used. One kind of theplasticizer may be used alone and two or more kinds thereof may be usedin combination.

Examples of the plasticizer include organic ester plasticizers such as amonobasic organic acid ester and a polybasic organic acid ester, organicphosphate plasticizers such as an organic phosphate plasticizer and anorganic phosphite plasticizer, and the like. It is preferred that theplasticizer be an organic ester plasticizer. It is preferred that theplasticizer be a liquid plasticizer.

Examples of the monobasic organic acid ester include a glycol esterobtained by the reaction of a glycol with a monobasic organic acid, andthe like. Examples of the glycol include triethylene glycol,tetraethylene glycol, tripropylene glycol, and the like. Examples of themonobasic organic acid include butyric acid, isobutyric acid, caproicacid, 2-ethylbutyric acid, heptanoic acid, n-octylic acid,2-ethylhexanoic acid, n-nonylic acid, decylic acid, benzoic acid and thelike.

Examples of the polybasic organic acid ester include an ester compoundof a polybasic organic acid and an alcohol having a linear or branchedstructure of 4 to 8 carbon atoms. Examples of the polybasic organic acidinclude adipic acid, sebacic acid, azelaic acid, and the like.

Examples of the organic ester plasticizer include triethylene glycoldi-2-ethylpropanoate, triethylene glycol di-2-ethylbutyrate, triethyleneglycol di-2-ethylhexanoate, triethylene glycol dicaprylate, triethyleneglycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethyleneglycol di-n-heptanoate, dibutyl sebacate, dioctyl azelate, dibutylcarbitol adipate, ethylene glycol di-2-ethylbutyrate, 1,3-propyleneglycol di-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate,diethylene glycol di-2-ethylbutyrate, diethylene glycoldi-2-ethylhexanoate, dipropylene glycol di-2-ethylbutyrate, triethyleneglycol di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate,diethylene glycol dicaprylate, diethylene glycol dibenzoate, dipropyleneglycol dibenzoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyladipate, a mixture of heptyl adipate and nonyl adipate, diisononyladipate, diisodecyl adipate, heptyl nonyl adipate, dibutyl sebacate,oil-modified sebacic alkyds, a mixture of a phosphoric acid ester and anadipic acid ester, and the like. Organic ester plasticizers other thanthese may be used. Other adipic acid esters other than theabove-described adipic acid esters may be used.

Examples of the organic phosphate plasticizer include tributoxyethylphosphate, isodecyl phenyl phosphate, triisopropyl phosphate, and thelike.

It is preferred that the plasticizer be a diester plasticizerrepresented by the following formula (1).

In the foregoing formula (1), R1 and R2 each represent an organic groupwith 5 to 10 carbon atoms, R3 represents an ethylene group, anisopropylene group, or an n-propylene group, and p represents an integerof 3 to 10. It is preferred that R1 and R2 in the foregoing formula (1)each be an organic group with 6 to 10 carbon atoms.

It is preferred that the plasticizer include triethylene glycoldi-2-ethylhexanoate (3GO), triethylene glycol di-2-ethylbutyrate (3GH)or triethylene glycol di-2-ethylpropanoate. It is more preferred thatthe plasticizer include triethylene glycol di-2-ethylhexanoate (3GO) ortriethylene glycol di-2-ethylbutyrate (3GH), and it is further preferredthat the plasticizer include triethylene glycol di-2-ethylhexanoate.

In the interlayer film, a content of the plasticizer (0) relative to 100parts by weight of the resin (0) (when the resin (0) is thermoplasticresin (0), 100 parts by weight of the thermoplastic resin (0); when theresin (0) is polyvinyl acetal resin (0), 100 parts by weight of thepolyvinyl acetal resin (0)) is referred to as content (0). The content(0) is preferably 25 parts by weight or more, more preferably 30 partsby weight or more, and is preferably 100 parts by weight or less, morepreferably 60 parts by weight or less, further preferably 50 parts byweight or less. When the content (0) is the above lower limit or more,the penetration resistance of laminated glass is further enhanced. Whenthe content (0) is the above upper limit or less, the transparency ofthe interlayer film is further enhanced.

In the first layer, a content of the plasticizer (1) relative to 100parts by weight of the resin (1) (when the resin (1) is thermoplasticresin (1), 100 parts by weight of the thermoplastic resin (1); when theresin (1) is polyvinyl acetal resin (1), 100 parts by weight of thepolyvinyl acetal resin (1)) is referred to as content (1). The content(1) is preferably 50 parts by weight or more, more preferably 55 partsby weight or more, further preferably 60 parts by weight or more, and ispreferably 100 parts by weight or less, more preferably 90 parts byweight or less, further preferably 85 parts by weight or less,especially preferably 80 parts by weight or less. When the content (1)is the above lower limit or more, the flexibility of the interlayer filmis enhanced and the handling of the interlayer film is facilitated. Whenthe content (1) is the above upper limit or less, the penetrationresistance of laminated glass is further enhanced.

In the second layer, a content of the plasticizer (2) relative to 100parts by weight of the resin (2) (when the resin (2) is thermoplasticresin (2), 100 parts by weight of the thermoplastic resin (2); when theresin (2) is polyvinyl acetal resin (2), 100 parts by weight of thepolyvinyl acetal resin (2)) is referred to as content (2). In the thirdlayer, a content of the plasticizer (3) relative to 100 parts by weightof the resin (3) (when the resin (3) is thermoplastic resin (3), 100parts by weight of the thermoplastic resin (3); when the resin (3) ispolyvinyl acetal resin (3), 100 parts by weight of the polyvinyl acetalresin (3)) is referred to as content (3). Each of the content (2) andthe content (3) is preferably 10 parts by weight or more, morepreferably 15 parts by weight or more, further preferably 20 parts byweight or more, especially preferably 24 parts by weight or more, andmost preferably 25 parts by weight or more. Each of the content (2) andthe content (3) is preferably 45 parts by weight or less, morepreferably 40 parts by weight or less, further preferably 35 parts byweight or less, especially preferably 32 parts by weight or less, andmost preferably 30 parts by weight or less. When the content (2) and thecontent (3) are the above lower limit or more, the flexibility of theinterlayer film is enhanced and the handling of the interlayer film isfacilitated. When the content (2) and the content (3) are the aboveupper limit or less, the penetration resistance of laminated glass isfurther enhanced.

For the purpose of heightening the sound insulating properties oflaminated glass, it is preferred that the content (1) be larger than thecontent (2) and it is preferred that the content (1) be larger than thecontent (3).

From the viewpoint of further enhancing the sound insulating property oflaminated glass, each of the absolute value of difference between thecontent (2) and the content (1) and the absolute value of differencebetween the content (3) and the content (1) is preferably 10 parts byweight or more, more preferably 15 parts by weight or more, and furtherpreferably 20 parts by weight or more. Each of the absolute value ofdifference between the content (2) and the content (1) and the absolutevalue of difference between the content (3) and the content (1) ispreferably 80 parts by weight or less, more preferably 75 parts byweight or less, further preferably 70 parts by weight or less.

(Heat Shielding Substance)

It is preferred that the interlayer film contain a heat shieldingsubstance (heat shielding compound). It is preferred that the firstlayer contain a heat shielding substance. It is preferred that thesecond layer contain a heat shielding substance. It is preferred thatthe third layer contain a heat shielding substance. One kind of the heatshielding substance may be used alone, and two or more kinds thereof maybe used in combination.

It is preferred that the heat shielding substance contain at least onekind of Ingredient X among a phthalocyanine compound, a naphthalocyaninecompound, and an anthracyanine compound or contain heat shieldingparticles. In this case, the heat shielding compound may be constitutedof both of the Ingredient X and the heat shielding particles.

Ingredient X:

It is preferred that the interlayer film include at least one kind ofIngredient X among a phthalocyanine compound, a naphthalocyaninecompound, and an anthracyanine compound. It is preferred that the firstlayer contain the Ingredient X. It is preferred that the second layercontain the Ingredient X. It is preferred that the third layer containthe Ingredient X. The Ingredient X is a heat shielding substance. Onekind of the Ingredient X may be used alone, and two or more kindsthereof may be used in combination.

The Ingredient X is not particularly limited. As the Ingredient X,conventionally known phthalocyanine compound, naphthalocyanine compoundand anthracyanine compound can be used.

Examples of the Ingredient X include phthalocyanine, a derivative ofphthalocyanine, naphthalocyanine, a derivative of naphthalocyanine,anthracyanine, a derivative of anthracyanine, and the like. It ispreferred that each of the phthalocyanine compound and the derivative ofphthalocyanine have a phthalocyanine skeleton. It is preferred that eachof the naphthalocyanine compound and the derivative of naphthalocyaninehave a naphthalocyanine skeleton. It is preferred that each of theanthracyanine compound and the derivative of anthracyanine have ananthracyanine skeleton.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof, itis preferred that the Ingredient X be at least one kind selected fromthe group consisting of phthalocyanine, a derivative of phthalocyanine,naphthalocyanine and a derivative of naphthalocyanine, and it is morepreferred that the Ingredient X be at least one kind amongphthalocyanine and a derivative of phthalocyanine.

From the viewpoints of effectively enhancing the heat shieldingproperties and maintaining the visible light transmittance at a higherlevel over a long period of time, it is preferred that the Ingredient Xcontain vanadium atoms or copper atoms. It is preferred that theIngredient X contain vanadium atoms and it is also preferred that theIngredient X contain copper atoms. It is more preferred that theIngredient X be at least one kind among phthalocyanine containingvanadium atoms or copper atoms and a derivative of phthalocyaninecontaining vanadium atoms or copper atoms. With regard to the interlayerfilm and laminated glass, from the viewpoint of still further enhancingthe heat shielding properties thereof, it is preferred that theIngredient X have a structural unit in which an oxygen atom is bonded toa vanadium atom.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the Ingredient X (a first layer, a second layer, or a thirdlayer), the content of the Ingredient X is preferably 0.001% by weightor more, more preferably 0.005% by weight or more, further preferably0.01% by weight or more, especially preferably 0.02% by weight or more.In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the Ingredient X (a first layer, a second layer, or a thirdlayer), the content of the Ingredient X is preferably 0.2% by weight orless, more preferably 0.1% by weight or less, further preferably 0.05%by weight or less, especially preferably 0.04% by weight or less. Whenthe content of the Ingredient X is the above lower limit or more and theabove upper limit or less, the heat shielding properties aresufficiently enhanced and the visible light transmittance issufficiently enhanced. For example, it is possible to make the visiblelight transmittance 70% or more.

Heat Shielding Particles:

It is preferred that the interlayer film contain heat shieldingparticles. It is preferred that the first layer contain the heatshielding particles. It is preferred that the second layer contain theheat shielding particles. It is preferred that the third layer containthe heat shielding particles. The heat shielding particle is of a heatshielding substance. By the use of heat shielding particles, infraredrays (heat rays) can be effectively cut off. One kind of the heatshielding particles may be used alone, and two or more kinds thereof maybe used in combination.

From the viewpoint of further enhancing the heat shielding property ofthe laminated glass, it is more preferred that the heat shieldingparticles be metal oxide particles. It is preferred that the heatshielding particle be a particle (a metal oxide particle) formed from anoxide of a metal.

The energy amount of an infrared ray with a wavelength of 780 nm orlonger which is longer than that of visible light is small as comparedwith an ultraviolet ray. However, the thermal action of infrared rays islarge, and when infrared rays are absorbed into a substance, heat isreleased from the substance. Accordingly, infrared rays are generallycalled heat rays. By the use of the heat shielding particles, infraredrays (heat rays) can be effectively cut off. In this connection, theheat shielding particle means a particle capable of absorbing infraredrays.

Specific examples of the heat shielding particles include metal oxideparticles such as aluminum-doped tin oxide particles, indium-doped tinoxide particles, antimony-doped tin oxide particles (ATO particles),gallium-doped zinc oxide particles (GZO particles), indium-doped zincoxide particles (IZO particles), aluminum-doped zinc oxide particles(AZO particles), niobium-doped titanium oxide particles, sodium-dopedtungsten oxide particles, cesium-doped tungsten oxide particles,thallium-doped tungsten oxide particles, rubidium-doped tungsten oxideparticles, tin-doped indium oxide particles (ITO particles), tin-dopedzinc oxide particles and silicon-doped zinc oxide particles, lanthanumhexaboride (LaB₆) particles, and the like. Heat shielding particlesother than these may be used. Since the heat ray shielding function ishigh, preferred are metal oxide particles, more preferred are ATOparticles, GZO particles, IZO particles, ITO particles or tungsten oxideparticles, and especially preferred are ITO particles or tungsten oxideparticles.

In particular, since the heat ray shielding function is high and theparticles are readily available, preferred are tin-doped indium oxideparticles (ITO particles), and also preferred are tungsten oxideparticles.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof, itis preferred that the tungsten oxide particles be metal-doped tungstenoxide particles. Examples of the “tungsten oxide particles” includemetal-doped tungsten oxide particles. Specifically, examples of themetal-doped tungsten oxide particles include sodium-doped tungsten oxideparticles, cesium-doped tungsten oxide particles, thallium-dopedtungsten oxide particles, rubidium-doped tungsten oxide particles, andthe like.

With regard to the interlayer film and laminated glass, from theviewpoint of further enhancing the heat shielding properties thereof,cesium-doped tungsten oxide particles are especially preferred. Withregard to the interlayer film and laminated glass, from the viewpoint ofstill further enhancing the heat shielding properties thereof, it ispreferred that the cesium-doped tungsten oxide particles be tungstenoxide particles represented by the formula: Cs_(0.33)WO₃.

The average particle diameter of the heat shielding particles ispreferably 0.01 μm or more, more preferably 0.02 μm or more, and ispreferably 0.1 μm or less, more preferably 0.05 μm or less. When theaverage particle diameter is the above lower limit or more, the heat rayshielding properties are sufficiently enhanced. When the averageparticle diameter is the above upper limit or less, the dispersibilityof heat shielding particles is enhanced.

The “average particle diameter” refers to the volume average particlediameter. The average particle diameter can be measured using a particlesize distribution measuring apparatus (“UPA-EX150” available fromNIKKISO CO., LTD.), or the like.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the heat shielding particles (a first layer, a second layer,or a third layer), each content of the heat shielding particles (inparticular, the content of tungsten oxide particles) is preferably 0.01%by weight or more, more preferably 0.1% by weight or more, furtherpreferably 1% by weight or more, especially preferably 1.5% by weight ormore. In 100% by weight of the interlayer film or in 100% by weight of alayer containing the heat shielding particles (a first layer, a secondlayer, or a third layer), each content of the heat shielding particles(in particular, the content of tungsten oxide particles) is preferably6% by weight or less, more preferably 5.5% by weight or less, furtherpreferably 4% by weight or less, especially preferably 3.5% by weight orless, most preferably 3% by weight or less. When the content of the heatshielding particles is the above lower limit or more and the above upperlimit or less, the heat shielding property is sufficiently enhanced andthe visible light transmittance is sufficiently enhanced.

(Metal Salt)

It is preferred that the interlayer film contain at least one kind ofmetal salt (hereinafter, sometimes described as Metal salt M) among analkali metal salt, an alkaline earth metal salt, and a magnesium salt.It is preferred that the first layer contain the Metal salt M. It ispreferred that the second layer contain the Metal salt M. It ispreferred that the third layer contain the Metal salt M. By the use ofthe Metal salt M, controlling the adhesivity between the interlayer filmand a lamination glass member such as a glass plate or the adhesivitybetween respective layers in the interlayer film is facilitated. Onekind of the Metal salt M may be used alone, and two or more kindsthereof may be used in combination.

It is preferred that the Metal salt M contain at least one kind of metalselected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr andBa. It is preferred that the metal salt contained in the interlayer filmcontain at least one kind of metal between K and Mg.

Moreover, it is more preferred that the Metal salt M be an alkali metalsalt of an organic acid with 2 to 16 carbon atoms, an alkaline earthmetal salt of an organic acid with 2 to 16 carbon atoms, and a magnesiumsalt of an organic acid with 2 to 16 carbon atoms, and it is furtherpreferred that the Metal salt M be a magnesium carboxylate with 2 to 16carbon atoms or a potassium carboxylate with 2 to 16 carbon atoms.

Examples of the magnesium carboxylate with 2 to 16 carbon atoms and thepotassium carboxylate with 2 to 16 carbon atoms include magnesiumacetate, potassium acetate, magnesium propionate, potassium propionate,magnesium 2-ethylbutyrate, potassium 2-ethylbutanoate, magnesium2-ethylhexanoate, potassium 2-ethylhexanoate, and the like.

The total of the contents of Mg and K in the interlayer film containingthe Metal salt M or a layer containing the Metal salt M (a first layer,a second layer, or a third layer) is preferably 5 ppm or more, morepreferably 10 ppm or more, further preferably 20 ppm or more, and ispreferably 300 ppm or less, more preferably 250 ppm or less, furtherpreferably 200 ppm or less. When the total of the contents of Mg and Kis the above lower limit or more and the above upper limit or less, theadhesivity between the interlayer film and a glass plate or theadhesivity between respective layers in the interlayer film can befurther well controlled.

(Ultraviolet Ray Screening Agent)

It is preferred that the interlayer film contain an ultraviolet rayscreening agent. It is preferred that the first layer contain anultraviolet ray screening agent. It is preferred that the second layercontain an ultraviolet ray screening agent. It is preferred that thethird layer contain an ultraviolet ray screening agent. By the use of anultraviolet ray screening agent, even when the interlayer film and thelaminated glass are used for a long period of time, the visible lighttransmittance becomes further hard to be lowered. One kind of theultraviolet ray screening agent may be used alone, and two or more kindsthereof may be used in combination.

Examples of the ultraviolet ray screening agent include an ultravioletray absorber. It is preferred that the ultraviolet ray screening agentbe an ultraviolet ray absorber.

Examples of the ultraviolet ray screening agent include an ultravioletray screening agent containing a metal atom, an ultraviolet rayscreening agent containing a metal oxide, an ultraviolet ray screeningagent having a benzotriazole structure (a benzotriazole compound), anultraviolet ray screening agent having a benzophenone structure (abenzophenone compound), an ultraviolet ray screening agent having atriazine structure (a triazine compound), an ultraviolet ray screeningagent having a malonic acid ester structure (a malonic acid estercompound), an ultraviolet ray screening agent having an oxanilidestructure (an oxanilide compound), an ultraviolet ray screening agenthaving a benzoate structure (a benzoate compound), and the like.

Examples of the ultraviolet ray screening agent containing a metal atominclude platinum particles, particles in which the surface of platinumparticles is coated with silica, palladium particles, particles in whichthe surface of palladium particles is coated with silica, and the like.It is preferred that the ultraviolet ray screening agent not be heatshielding particles.

The ultraviolet ray screening agent is preferably an ultraviolet rayscreening agent having a benzotriazole structure, an ultraviolet rayscreening agent having a benzophenone structure, an ultraviolet rayscreening agent having a triazine structure, or an ultraviolet rayscreening agent having a benzoate structure. The ultraviolet rayscreening agent is more preferably an ultraviolet ray screening agenthaving a benzotriazole structure or an ultraviolet ray screening agenthaving a benzophenone structure, and is further preferably anultraviolet ray screening agent having a benzotriazole structure.

Examples of the ultraviolet ray screening agent containing a metal oxideinclude zinc oxide, titanium oxide, cerium oxide, and the like.Furthermore, with regard to the ultraviolet ray screening agentcontaining a metal oxide, the surface thereof may be coated with anymaterial. Examples of the coating material for the surface of theultraviolet ray screening agent containing a metal oxide include aninsulating metal oxide, a hydrolyzable organosilicon compound, asilicone compound, and the like.

Examples of the insulating metal oxide include silica, alumina,zirconia, and the like. For example, the insulating metal oxide has aband-gap energy of 5.0 eV or more.

Examples of the ultraviolet ray screening agent having a benzotriazolestructure include 2-(2′-hydroxy-5′-methylphenyl)benzotriazole (“TinuvinP” available from BASF Japan Ltd.),2-(2′-hydroxy-3′,5′-di-t-butylphenyl)benzotriazole (“Tinuvin 320”available from BASF Japan Ltd.),2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole (“Tinuvin326” available from BASF Japan Ltd.),2-(2′-hydroxy-3′,5′-di-amylphenyl)benzotriazole (“Tinuvin 328” availablefrom BASF Japan Ltd.), and the like. It is preferred that theultraviolet ray screening agent be an ultraviolet ray screening agenthaving a benzotriazole structure containing a halogen atom, and it ismore preferred that the ultraviolet ray screening agent be anultraviolet ray screening agent having a benzotriazole structurecontaining a chlorine atom, because those are excellent in ultravioletray screening performance.

Examples of the ultraviolet ray screening agent having a benzophenonestructure include octabenzone (“Chimassorb 81” available from BASF JapanLtd.), and the like.

Examples of the ultraviolet ray screening agent having a triazinestructure include “LA-F70” available from ADEKA CORPORATION,2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (“Tinuvin1577FF” available from BASF Japan Ltd.), and the like.

Examples of the ultraviolet ray screening agent having a malonic acidester structure include dimethyl 2-(p-methoxybenzylidene)malonate,tetraethyl-2,2-(1,4-phenylenedimethylidene)bismalonate,2-(p-methoxybenzylidene)-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)malonate,and the like.

Examples of a commercial product of the ultraviolet ray screening agenthaving a malonic acid ester structure include Hostavin B-CAP, HostavinPR-25 and Hostavin PR-31 (any of these is available from Clariant JapanK.K.).

Examples of the ultraviolet ray screening agent having an oxanilidestructure include a kind of oxalic acid diamide having a substitutedaryl group and the like on the nitrogen atom such asN-(2-ethylphenyl)-N′-(2-ethoxy-5-t-butylphenyl)oxalic acid diamide,N-(2-ethylphenyl)-N′-(2-ethoxy-phenyl)oxalic acid diamide and2-ethyl-2′-ethoxy-oxanilide (“Sanduvor VSU” available from ClariantJapan K.K.).

Examples of the ultraviolet ray screening agent having a benzoatestructure include2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (“Tinuvin120” available from BASF Japan Ltd.), and the like.

In 100% by weight of the interlayer film or in 100% by weight of a layercontaining the ultraviolet ray screening agent (a first layer, a secondlayer, or a third layer), the content of the ultraviolet ray screeningagent and the content of the benzotriazole compound are preferably 0.1%by weight or more, more preferably 0.2% by weight or more, furtherpreferably 0.3% by weight or more, especially preferably 0.5% by weightor more. In 100% by weight of the interlayer film or in 100% by weightof a layer containing the ultraviolet ray screening agent (a firstlayer, a second layer, or a third layer), the content of the ultravioletray screening agent and the content of the benzotriazole compound arepreferably 2.5% by weight or less, more preferably 2% by weight or less,further preferably 1% by weight or less, especially preferably 0.8% byweight or less. When the content of the ultraviolet ray screening agentis the above-described lower limit or more and the above-described upperlimit or less, deterioration in visible light transmittance after alapse of a period can be further suppressed. In particular, by settingthe content of the ultraviolet ray screening agent to be 0.2% by weightor more in 100% by weight of a layer containing the ultraviolet rayscreening agent, with regard to the interlayer film and laminated glass,the lowering in visible light transmittance thereof after the lapse of acertain period of time can be significantly suppressed.

(Oxidation Inhibitor)

It is preferred that the interlayer film contain an oxidation inhibitor.It is preferred that the first layer contain an oxidation inhibitor. Itis preferred that the second layer contain an oxidation inhibitor. It ispreferred that the third layer contain an oxidation inhibitor. One kindof the oxidation inhibitor may be used alone, and two or more kindsthereof may be used in combination.

Examples of the oxidation inhibitor include a phenol-based oxidationinhibitor, a sulfur-based oxidation inhibitor, a phosphorus-basedoxidation inhibitor, and the like. The phenol-based oxidation inhibitoris an oxidation inhibitor having a phenol skeleton. The sulfur-basedoxidation inhibitor is an oxidation inhibitor containing a sulfur atom.The phosphorus-based oxidation inhibitor is an oxidation inhibitorcontaining a phosphorus atom.

It is preferred that the oxidation inhibitor be a phenol-based oxidationinhibitor or a phosphorus-based oxidation inhibitor.

Examples of the phenol-based oxidation inhibitor include2,6-di-t-butyl-p-cresol (BHT), butyl hydroxyanisole (BHA),2,6-di-t-butyl-4-ethylphenol, stearylβ-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,2,2′-methylenebis-(4-methyl-6-butylphenol),2,2′-methylenebis-(4-ethyl-6-t-butylphenol),4,4′-butylidene-bis-(3-methyl-6-t-butylphenol),1,1,3-tris-(2-methyl-hydroxy-5-t-butylphenyl)butane,tetrakis[methylene-3-(3′,5′-butyl-4-hydroxyphenyl)propionate]methane,1,3,3-tris-(2-methyl-4-hydroxy-5-t-butylphenol)butane,1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,bis(3,3′-t-butylphenol)butyric acid glycol ester,bis(3-t-butyl-4-hydroxy-5-methylbenzenepropanoicacid)ethylenebis(oxyethylene), and the like. One kind or two or morekinds among these oxidation inhibitors are preferably used.

Examples of the phosphorus-based oxidation inhibitor include tridecylphosphite, tris(tridecyl) phosphite, triphenyl phosphite, trinonylphenylphosphite, bis(tridecyl)pentaerithritol diphosphite,bis(decyl)pentaerithritol diphosphite, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butyl-6-methylphenyl)ethyl ester phosphorousacid, 2,2′-methylenebis(4,6-di-t-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus, and the like. One kind or two or more kindsamong these oxidation inhibitors are preferably used.

Examples of a commercial product of the oxidation inhibitor include“IRGANOX 245” available from BASF Japan Ltd., “IRGAFOS 168” availablefrom BASF Japan Ltd., “IRGAFOS 38” available from BASF Japan Ltd.,“Sumilizer BHT” available from Sumitomo Chemical Co., Ltd., “H-BHT”available from Sakai Chemical Industry Co., Ltd., “IRGANOX 1010”available from BASF Japan Ltd., and the like.

For maintaining high visible light transmittance of the interlayer filmand the laminated glass over a long period of time, it is preferred thatthe content of the oxidation inhibitor be 0.1% by weight or more in 100%by weight of the interlayer film or in 100% by weight of a layercontaining the oxidation inhibitor (a first layer, a second layer or athird layer). Moreover, since an effect commensurate with the additionof an oxidation inhibitor is not attained, it is preferred that thecontent of the oxidation inhibitor be 2% by weight or less in 100% byweight of the interlayer film or in 100% by weight of the layercontaining the oxidation inhibitor.

(Other Ingredients)

Each of the interlayer film, the first layer, the second layer, and thethird layer may contain additives such as a coupling agent, a dispersingagent, a surfactant, a flame retardant, an antistatic agent, a pigment,a dye, an adhesive force regulator other than metal salt, amoisture-resistance agent, a fluorescent brightening agent, and aninfrared ray absorber, as necessary. One kind of these additives may beused alone, and two or more kinds thereof may be used in combination.

(Laminated Glass)

FIG. 7 is a sectional view showing an example of a laminated glassprepared with the interlayer film for laminated glass shown in FIG. 1 .

A laminated glass 21 shown in FIG. 7 is provided with the interlayerfilm 11, a first lamination glass member 22, and a second laminationglass member 23. The interlayer film 11 is arranged between the firstlamination glass member 22 and the second lamination glass member 23 tobe sandwiched therebetween. The first lamination glass member 22 isarranged on a first surface of the interlayer film 11. The secondlamination glass member 23 is arranged on a second surface opposite tothe first surface of the interlayer film 11.

Examples of the lamination glass member include a glass plate, a PET(polyethylene terephthalate) film, and the like. As the laminated glass,laminated glass in which an interlayer film is sandwiched between aglass plate and a PET film or the like, as well as laminated glass inwhich an interlayer film is sandwiched between two glass plates, isincluded. The laminated glass is a laminate provided with a glass plate,and it is preferred that at least one glass plate be used. It ispreferred that each of the first lamination glass member and the secondlamination glass member be a glass plate or a PET (polyethyleneterephthalate) film and the interlayer film include at least one glassplate as the first lamination glass member or the second laminationglass member. It is especially preferred that both of the firstlamination glass member and the second lamination glass member be glassplates.

Examples of the glass plate include a sheet of inorganic glass and asheet of organic glass. Examples of the inorganic glass include floatplate glass, heat ray-absorbing plate glass, heat ray-reflecting plateglass, polished plate glass, figured glass, wired plate glass, greenglass, and the like. The organic glass is synthetic resin glasssubstituted for inorganic glass. Examples of the organic glass include apolycarbonate plate, a poly(meth)acrylic resin plate, and the like.Examples of the poly(meth)acrylic resin plate include a polymethyl(meth)acrylate plate, and the like.

Although respective thicknesses of the first lamination glass member andthe second lamination glass member are not particularly limited, thethickness is preferably 0.03 mm or more, more preferably 1 mm or moreand is preferably 5 mm or less. When the lamination glass member is aglass plate, the thickness of the glass plate is preferably 1 mm or moreand is preferably 5 mm or less. When the lamination glass member is aPET film, the thickness of the PET film is preferably 0.03 mm or moreand is preferably 0.5 mm or less.

The wedge angle of the first lamination glass member is 0 mrad or more(not being wedge-like shaped at 0 mrad). The wedge angle of the firstlamination glass member is preferably 0 mrad or more, more preferably0.05 mrad or more, still more preferably 0.10 mrad or more, furtherpreferably 0.15 mrad or more, especially preferably 0.20 mrad or more,most preferably 0.25 mrad or more. The wedge angle of the firstlamination glass member is preferably 2.0 mrad or less, more preferably1.5 mrad or less. When the wedge angle of the first lamination glassmember is the above lower limit or more and the above upper limit orless, it is possible to further suppress double images.

The wedge angle of the second lamination glass member is 0 mrad or more(not being wedge-like shaped at 0 mrad). The wedge angle of the secondlamination glass member is preferably 0 mrad or more, more preferably0.05 mrad or more, still more preferably 0.10 mrad or more, furtherpreferably 0.15 mrad or more, especially preferably 0.20 mrad or more,most preferably 0.25 mrad or more. The wedge angle of the secondlamination glass member is preferably 2.0 mrad or less, more preferably1.5 mrad or less. When the wedge angle of the first lamination glassmember is the above lower limit or more and the above upper limit orless, it is possible to further suppress double images.

The method for producing the laminated glass is not particularlylimited. First, the interlayer film is sandwiched between the firstlamination glass member and the second lamination glass member to obtaina laminate. Then, for example, by passing the obtained laminate throughpressure rolls or subjecting the obtained laminate to decompressionsuction in a rubber bag, the air remaining between the first laminationglass member and the interlayer film, and between the second laminationglass member and the interlayer film is removed. Then, the laminate ispreliminarily bonded together at about 70° C. to 110° C. to obtain apreliminarily press-bonded laminate. Next, by putting the preliminarilypress-bonded laminate into an autoclave or by pressing the laminate, thelaminate is press-bonded at about 120° C. to 150° C. and under apressure of 1 MPa to 1.5 MPa. In this way, laminated glass can beobtained.

The laminated glass can be used for automobiles, railway vehicles,aircraft, ships, buildings, and the like. It is preferred that thelaminated glass be laminated glass for buildings or for vehicles and itis more preferred that the laminated glass be laminated glass forvehicles. The laminated glass can also be used for applications otherthan these applications. The laminated glass can be used for awindshield, side glass, rear glass, or roof glass of an automobile, andthe like. Since the laminated glass is high in heat shielding propertiesand is high in visible light transmittance, the laminated glass issuitably used for automobiles.

The laminated glass is a kind of laminated glass serving as a head-updisplay (HUD). In the laminated glass, measured information such as thespeed which is sent from a control unit and the like can be projectedonto the windshield from a display unit of the instrumental panel.Accordingly, without making a driver of an automobile move his or hervisual field downward, a front visual field and measured information canbe visually recognized simultaneously.

Hereinafter, the present invention will be described in more detail withreference to examples and comparative examples. The present invention isnot limited only to these examples.

In polyvinyl acetal resins used, n-butyraldehyde which has 4 carbonatoms is used for the acetalization. With regard to the polyvinyl acetalresin, the acetalization degree (the butyralization degree), theacetylation degree and the content of the hydroxyl group were measuredby a method in accordance with JIS K6728 “Testing methods for polyvinylbutyral”. In this connection, even in the cases of being measuredaccording to ASTM D1396-92, numerical values similar to those obtainedby a method in accordance with JIS K6728 “Testing methods for polyvinylbutyral” were exhibited.

Example 1

Preparation of Composition for Forming First Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a first layer.

Polyvinyl acetal resin (average polymerization degree: 1700, content ofhydroxyl group: 30.5% by mole, acetylation degree: 1.0% by mole,acetalization degree: 68.5% by mole): 100 parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 40 parts by weight

An amount that is to be 0.2% by weight in the obtained interlayer filmof Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.)

An amount that is to be 0.2% by weight in the obtained interlayer filmof BHT (2,6-di-t-butyl-p-cresol)

Preparation of Interlayer Film:

The composition for forming a first layer was co-extruded by using anextruder. At this time, the temperature of the lip die was adjustedwithin the range of 100° C. to 280° C. so that a temperature gradientwas provided while taking the end part having a smaller thickness of theentire interlayer film in the width direction as a low temperature side,and the end part having a larger thickness of the entire interlayer filmas a high temperature side. The gap of the lip was adjusted within therange of 1.0 mm to 4.0 mm. The difference in speed of rolls throughwhich the resin film discharged from the lip die passes up to windingwas set to be 15% or less. The roll through which the resin dischargedfrom the lip die first passes was installed below the die and previousto the die in the machine direction, the extruding amount from theextruder was adjusted to 700 kg/h, and the speed of the roll throughwhich the resin film first passes was adjusted to 7 m/minute. In thismanner, a wedge-like shaped interlayer film having only the first layerwas prepared.

The obtained interlayer film has a minimum thickness at one end and hasa maximum thickness at the other end. A distance X between one end andthe other end was 105 cm.

In Example 1, an interlayer film having a portion where the increment ofthe thickness decreases from one end side to the other end side in aregion where the thickness increases, and having a portion where thewedge angle decreases from one end side to the other end side in aregion where the sectional shape in the thickness direction is awedge-like shape was prepared (see FIG. 5 for the contour shape). In theinterlayer film, when the distance between one end and the other end isreferred to as X, the peak of the projecting portion was located at 0.6Xfrom the one end. The wedge angle θ of the interlayer film as a wholewas 0.51 mrad.

Example 2

An interlayer film was prepared in the same manner as that in Example 1except that the temperature gradient of the lip die was gentled (seeFIG. 5 for the contour shape). The wedge angle θ of the interlayer filmas a whole was 0.30 mrad.

Example 3

An interlayer film was prepared in the same manner as that in Example 1except that the temperature gradient of the lip die was steepened (seeFIG. 3 for the contour shape). The wedge angle θ of the interlayer filmas a whole was 0.70 mrad.

Comparative Example 1

An interlayer film was prepared in the same manner as that in Example 1except that the adjusting range of the gap of the lip was changed (seeFIG. 1 for the contour shape). The wedge angle θ of the interlayer filmas a whole was 0.51 mrad.

Comparative Example 2

An interlayer film was prepared in the same manner as that in Example 1except that the temperature gradient of the lip die was gentled, and theadjusting range of the gap of the lip was changed (see FIG. 3 for thecontour shape). The wedge angle θ of the interlayer film as a whole was0.29 mrad.

Comparative Example 3

An interlayer film was prepared in the same manner as that in Example 1except that the temperature gradient of the lip die was steepened, andthe adjusting range of the gap of the lip was changed (see FIG. 3 forthe contour shape). The wedge angle θ of the interlayer film as a wholewas 0.75 mrad.

Example 4

In Example 4, an interlayer film having a portion where the increment ofthe thickness decreases from one end side to the other end side in aregion where the thickness increases, and having a portion where thewedge angle increases from one end side to the other end side in aregion where the sectional shape in the thickness direction is awedge-like shape was prepared (see FIG. 3 for the contour shape).

Preparation of Composition for Forming First Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a first layer.

Polyvinyl acetal resin (content of hydroxyl group: 22% by mole,acetylation degree: 13% by mole, acetalization degree: 65% by mole): 100parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 65 parts by weight

An amount that is to be 0.2% by weight in the obtained first layer ofTinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.)

An amount that is to be 0.2% by weight in the obtained first layer ofBHT (2,6-di-t-butyl-p-cresol)

Preparation of Composition for Forming Second Layer and Third Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a second layer and athird layer. Other ingredients were added to the polyvinyl acetal resin.

Polyvinyl acetal resin (content of hydroxyl group: 30.5% by mole,acetylation degree: 1% by mole, acetalization degree: 68.5% by mole):100 parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 38 parts by weight

An amount that is to be 0.2% by weight in the obtained second layer andthird layer of Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.)

An amount that is to be 0.2% by weight in the obtained second layer andthird layer of BHT (2,6-di-t-butyl-p-cresol)

Preparation of Interlayer Film:

The composition for forming the first layer, and the composition forforming the second layer and the third layer were coextruded by using aco-extruder. At this time, the temperature of the lip die was adjustedwithin the range of 100° C. to 280° C. so that a temperature gradientwas provided while taking the end part having a smaller thickness of theentire interlayer film in the width direction as a low temperature side,and the end part having a larger thickness of the entire interlayer filmas a high temperature side. The gap of the lip was adjusted within therange of 1.0 mm to 4.0 mm so that the difference in speed of rollsthrough which the resin film discharged from the lip die passes up towinding was 15% or less. The roll through which the resin filmdischarged from the lip die first passes was installed below the die andprevious to the die in the machine direction. The extruding amount fromthe extruder was 700 kg/h. The speed of the roll through which the resinfilm first passes was adjusted to 7 m/minute. In Example 4, afterextrusion molding of the interlayer film, the interlayer film was heatedand retained at 100° C. to 150° C. for 5 minutes or less, and thenreturned to the normal temperature. A wedge-like shaped interlayer filmhaving a multilayer structure of the second layer/the first layer/thethird layer was prepared. The interlayer film obtained in each ofExample 4, later-described Examples 5, 6 and Comparative Examples 4 to 6has a minimum thickness at one end and has a maximum thickness at theother end. In the interlayer film, when the distance between one end andthe other end is referred to as X, the deepest part of the recessportion was located at a position of 0.6× from the one end. The wedgeangle θ of the interlayer film as a whole was 0.50 mrad.

Example 5

An interlayer film was prepared in the same manner as that in Example 4except that the temperature gradient of the lip die was gentled (seeFIG. 1 ). The wedge angle θ of the interlayer film as a whole was 0.30mrad.

Example 6

An interlayer film was prepared in the same manner as that in Example 4except that the temperature gradient of the lip die was steepened (seeFIG. 5 ). The wedge angle θ of the interlayer film as a whole was 0.64mrad.

Comparative Example 4

An interlayer film was prepared in the same manner as that in Example 4except that the adjusting range of the gap of the lip was changed (seeFIG. 3 ). The wedge angle θ of the interlayer film as a whole was 0.58mrad.

Comparative Example 5

An interlayer film was prepared in the same manner as that in Example 4except that the temperature gradient of the lip die was gentled, and theadjusting range of the gap of the lip was changed (see FIG. 3 ). Thewedge angle θ of the interlayer film as a whole was 0.29 mrad.

Comparative Example 6

An interlayer film was prepared in the same manner as that in Example 4except that the temperature gradient of the lip die was steepened, andthe adjusting range of the gap of the lip was changed (see FIG. 5 ). Thewedge angle θ of the interlayer film as a whole was 0.36 mrad.

Example 7

In Example 7, an interlayer film having a portion where the increment ofthe thickness decreases from one end side to the other end side in aregion where the thickness increases, and having a portion where thewedge angle increases from one end side to the other end side in aregion where the sectional shape of the thickness direction is awedge-like shape was prepared. (see FIG. 5 for the contour shape).

Preparation of Composition for Forming First Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a first layer.

Polyvinyl acetal resin (content of hydroxyl group: 22% by mole,acetylation degree: 13% by mole, acetalization degree: 65% by mole): 100parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 65 parts by weight

Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.) 0.2 parts by weight

BHT (2,6-di-t-butyl-p-cresol) 0.2 parts by weight

Preparation of Composition for Forming Second Layer and Third Layer:

The following ingredients were mixed, and kneaded sufficiently with amixing roll to obtain a composition for forming a second layer and athird layer. Other ingredients were added to the polyvinyl acetal resin.

Polyvinyl acetal resin (content of hydroxyl group: 30.5% by mole,acetylation degree: 1% by mole, acetalization degree: 68.5% by mole):100 parts by weight

Triethylene glycol di-2-ethylhexanoate (3GO): 38 parts by weight

Tinuvin 326(2-(2′-hydroxy-3′-t-butyl-5-methylphenyl)-5-chlorobenzotriazole,“Tinuvin 326” available from BASF Japan Ltd.) 0.2 parts by weight

BHT (2,6-di-t-butyl-p-cresol) 0.2 parts by weight

Preparation of Interlayer Film:

The composition for forming the first layer, and the composition forforming the second layer and the third layer were coextruded by using aco-extruder. At this time, the temperature of the lip die was adjustedwithin the range of 100° C. to 280° C. so that a temperature gradientwas provided while taking the end part having a smaller thickness of theentire interlayer film in the width direction as a low temperature side,and the end part having a larger thickness of the entire interlayer filmas a high temperature side. The gap of the lip was adjusted within therange of 1.0 mm to 4.0 mm so that the difference in speed of rollsthrough which the resin film discharged from the lip die passes up towinding was 15% or less. The roll through which the resin filmdischarged from the lip die first passes was installed below the die andprevious to the die in the machine direction. The extruding amount fromthe extruder was 700 kg/h. The speed of the roll through which the resinfilm first passes was adjusted to 7 m/minute. In Example 7, afterextrusion molding of the interlayer film, the interlayer film was heatedand retained at 100° C. to 150° C. for 5 minutes or less, and thenreturned to the normal temperature. A wedge-like shaped interlayer filmhaving a multilayer structure of the second layer/the first layer/thethird layer was prepared. The interlayer film obtained in each ofExample 7, later-described Examples 8 to 10 and Comparative Examples 7to 9 has a minimum thickness at one end and has a maximum thickness atthe other end. In the interlayer film, when the distance between one endand the other end is referred to as X, the peak of the projectingportion was located at 0.6X from the one end. The wedge angle θ of theinterlayer film as a whole was 0.34 mrad.

Example 8

An interlayer film was prepared in the same manner as that in Example 7except that the temperature gradient of the lip die was steepened (seeFIG. 5 ). The wedge angle θ of the interlayer film as a whole was 0.54mrad.

Example 9

An interlayer film was prepared in the same manner as that in Example 7except that the temperature gradient of the lip die was gentled (seeFIG. 5 ). The wedge angle θ of the interlayer film as a whole was 0.26mrad.

Example 10

An interlayer film was prepared in the same manner as that in Example 9except that the temperature gradient of the lip die was steepened, andthe adjusting range of the gap of the lip was changed (see FIG. 3 ). Thewedge angle θ of the interlayer film as a whole was 0.45 mrad.

Example 11

An interlayer film was prepared in the same manner as that in Example 10except that the temperature gradient of the lip die was steepened, andthe adjusting range of the gap of the lip was changed (see FIG. 3 ). Thewedge angle θ of the interlayer film as a whole was 0.62 mrad. In theinterlayer film, when the distance between one end and the other end isreferred to as X, the deepest part of the recess portion was located ata position of 0.6X from the one end.

Comparative Example 7

An interlayer film was prepared in the same manner as that in Example 7except that the temperature gradient of the lip die was steepened, andthe adjusting range of the gap of the lip was changed (see FIG. 5 ). Thewedge angle θ of the interlayer film as a whole was 0.50 mrad.

Comparative Example 8

An interlayer film was prepared in the same manner as that in Example 7except that the adjusting range of the gap of the lip was changed (seeFIG. 5 ). The wedge angle θ of the interlayer film as a whole was 0.27mrad.

Comparative Example 9

An interlayer film was prepared in the same manner as that in Example 7except that the temperature gradient of the lip die was steepened, andthe adjusting range of the gap of the lip was changed (see FIG. 5 ). Thewedge angle θ of the interlayer film as a whole was 0.43 mrad.

(Evaluation)

(1) Measurement of Partial Wedge Angle

The region for display in the interlayer films obtained in Examples andComparative Examples is a region between 10 cm and 59.5 cm from one endof the interlayer film. Therefore, the partial wedge angle φ_(x) and thepartial wedge angle φ_(y), the partial wedge angle A_(x) and the partialwedge angle A_(y), the partial wedge angle B_(x) and the partial wedgeangle B_(y), and the partial wedge angle C_(x) and the partial wedgeangle C_(y), respectively have the same angle.

In the obtained interlayer film, partial wedge angle φ_(x) and partialwedge angle φ_(y) in the region between a position of 10 cm and aposition of 59.5 cm from the one end toward the other end of theinterlayer film (region R, region for display) were calculated.

In the obtained interlayer film, partial wedge angle A_(x) and partialwedge angle A_(y) in the region between a position of 10 cm and aposition of 26.5 cm from the one end toward the other end of theinterlayer film (first partial region, first partial region for display)were calculated.

In the obtained interlayer film, partial wedge angle B_(x) and partialwedge angle B_(y) in the region between a position of 26.5 cm and aposition of 43 cm from the one end toward the other end of theinterlayer film (second partial region, second partial region fordisplay) were calculated.

In the obtained interlayer film, partial wedge angle C_(x) and partialwedge angle C_(y) in the region between a position of 43 cm and aposition of 59.5 cm from the one end toward the other end of theinterlayer film (third partial region, third partial region for display)were calculated.

In the obtained interlayer film, difference between the maximum valueand the minimum value in the partial region Ψ was calculated.

(2) Double Images

A pair of glass plates (clear glass, the size of 510 mm×910 mm, 2.0 mmin thickness) was prepared. An interlayer film with a size correspondingto the size of the glass plate was sandwiched between the pair of glassplates to obtain a laminate. As shown in FIG. 9 , the obtained laminatewas fitted into a frame of an EPDM-made rubber tube (frame member). Therubber tube has a width of 15 mm. Next, the laminate fitted into a frameof an EPDM-made rubber tube was preliminarily press-bonded by a vacuumbag method. The preliminarily press-bonded laminate was subjected topress-bonding at 150° C. and a pressure of 1.2 MPa with the use of anautoclave to obtain a sheet of laminated glass.

For the obtained laminated glass, double images were evaluated by thefollowing evaluation method.

(2-1) Evaluation of Double Images by Visual Check

(2-1-1) Evaluation of Double Images by Difference in Focal Distance

The obtained sheet of laminated glass was installed at a position of thewindshield. The information to be displayed, which is emitted from adisplay unit (focal distance: 2 m, 3 m, and 4 m) installed below thelaminated glass, was reflected by the sheet of laminated glass tovisually confirm the presence or absence of double images at aprescribed position (the entire region for display). The double imageswere judged according to the following criteria.

[Criteria for Judgement in Evaluation of Double Images by Visual Check]

oo: Double images are not confirmed.

o: Double images are confirmed very slightly, but are at a level causingno problem in practical use.

x: Not corresponding to the criteria of oo and o.

(2-1-2) Evaluation of Double Images by Observers with Different SeatedHeights

The obtained sheet of laminated glass was installed at a position of thewindshield. The information to be displayed, which is emitted from adisplay unit (focal distance: 3 m) installed below the laminated glass,was reflected by the sheet of laminated glass to visually confirm thepresence or absence of double images at a prescribed position (theentire region for display). Three observes having seated heights of 85cm, 90 cm, and 95 cm, respectively judged double images according to thefollowing criteria.

[Criteria for Judgement in Evaluation of Double Images by Visual Check]

oo: Double images are not confirmed by three observers.

o: Double images are confirmed very slightly by one observer, but are ata level causing no problem in practical use.

x: Not corresponding to the criteria of oo and o.

(2-2) Evaluation of Double Images by Device

Double image distance was evaluated by using “double image evaluationdevice” available from Oxide Corporation. An image projected from theprojector (HUD image) was reflected on a laminated glass, andphotographed by a camera. From the photographed image, a double imagedistance was measured. The distance from the projector to the camera(optical length) was 3 m. The reflection angle was the angle obtained byoptical path calculation simulation based on the wedge angle of the HUDarea.

[Criteria for Judgement in Evaluation of Double Images by Device]

oo: Double image distance is 0 mm or more and less than 1.0 mm.

o: Double image distance is 1.0 mm or more and less than 1.5 mm.

x: Double image distance is 1.5 mm or more and less than 2.0 mm.

The details and the results are shown in the following Tables 1 to 4.

TABLE 1 Comparative Comparative Comparative Example 1 Example 2 Example3 Example 1 Example 2 Example 3 Configuration of interlayer filmOne-layer One-layer One-layer One-layer One-layer One-layer Contourshape FIG. 5 FIG. 5 FIG. 3 FIG. 1 FIG. 3 FIG. 3 Maximum thickness ininterlayer film μm 1274 1068 1468 1277 1059 151.8 Minimum thickness ininterlayer film μm 760 760 760 760 760 760 Wedge angle θ of wholeinterlayer film mrad 0.51 0.30 0.70 0.51 0.29 0.75 Partial wedge angleϕ_(x) in region for display mrad 0.53 0.31 0.69 0.51 0.27 0.73 Partialwedge angle ϕ_(y) in region R Partial wedge angle A_(x) in first partialregion mrad 0.55 0.35 0.72 0.58 0.34 0.67 for display Partial wedgeangle A_(γ) in first partial region Partial wedge angle B_(x) in secondpartial region mrad 0.53 0.30 0.70 0.45 0.24 0.77 for display Partialwedge angle B_(y) in second partial region Partial wedge angle C_(x) inthird partial region mrad 0.50 0.28 0.65 0.56 0.26 0.71 for displayPartial wedge angle C_(y) in third partial region Difference betweenmaximum value and minimum mrad 0.15 0.11 0.12 0.14 0.10 0.13 value ofpartial region ψ |A_(x) − ϕ_(x)| and |A_(y) − ϕ_(y)| mrad 0.02 0.04 0.030.07 0.07 0.06 |B_(x) − ϕ_(x)| and |B_(y) − ϕ_(y)| mrad 0.00 0.01 0.010.06 0.03 0.04 |C_(x) − ϕ_(x)| and |C_(y) − ϕ_(y)| mrad 0.03 0.03 0.040.05 0.01 0.02 Double Visual Double image (focal distance: 2 m) ○○ ○ ○ ○○ ○ images check Double image (focal distance: 3 m) ○○ ○ ○ x x x Doubleimage (focal distance: 4 m) ○○ ○ ○ x x x Double image (observers with ○○○○ ○○ x x x different seated heights) Device Double image (focaldistance: 3 m) ○○ ○ ○ x x x

TABLE 2 Comparative Comparative Comparative Example 4 Example 5 Example6 Example 4 Example 5 Example 6 Configuration of interlayer filmThree-layer Three-layer Three-layer Three-layer Three-layer Three-layerContour shape FIG. 3 FIG. 1 FIG. 5 FIG. 3 FIG. 3 FIG. 5 Maximumthickness in interlayer film μm 1269 1065 1472 1324 1058 1066 Minimumthickness in interlayer film μm 760 760 760 760 760 760 Wedge angle θ ofwhole interlayer film mrad 0.50 0.30 0.64 0.58 0.29 0.36 Partial wedgeangle ϕ_(x) in region for display mrad 0.50 0.30 0.71 0.55 0.28 0.66Partial wedge angle ϕ_(y) in region R Partial wedge angle A_(x) in firstpartial region mrad 0.51 0.30 0.73 0.49 0.22 0.62 for display Partialwedge angle A_(γ) in first partial region Partial wedge angle B_(x) insecond partial region mrad 0.50 0.30 0.72 0.56 0.28 0.66 for displayPartial wedge angle B_(y) in second partial region Partial wedge angleC_(x) in third partial region mrad 0.50 0.30 0.66 0.58 0.33 0.72 fordisplay Partial wedge angle C_(y) in third partial region Differencebetween maximum value and minimum mrad 0.13 0.12 0.14 0.14 0.13 0.11value of partial region ψ |A_(x) − ϕ_(x)| and |A_(y) − ϕ_(y)| mrad 0.010.00 0.02 0.06 0.06 0.04 |B_(x) − ϕ_(x)| and |B_(y) − ϕ_(y)| mrad 0.000.00 0.01 0.01 0.00 0.00 |C_(x) − ϕ_(x)| and |C_(y) − ϕ_(y)| mrad 0.000.00 0.05 0.03 0.05 0.06 Double Visual Double image (focal distance: 2m) ○○ ○○ ○ ○ ○ ○ images check Double image (focal distance: 3 m) ○○ ○○ ○x x x Double image (focal distance: 4 m) ○○ ○○ ○ x x x Double image(observers with ○○ ○○ ○○ x x x different seated heights) Device Doubleimage (focal distance: 3 m) ○○ ○○ ○ x x x

TABLE 3 Example 7 Example 8 Example 9 Example 10 Example 11Configuration of interlayer film Three-layer Three-layer Three-layerThree-layer Three-layer Contour shape FIG. 5 FIG. 5 FIG. 5 FIG. 3 FIG. 3Maximum thickness in interlayer film μm 1077 1257 1004 1183 1349 Minimumthickness in interlayer film μm 760 760 760 760 760 Wedge angle θ ofwhole interlayer film mrad 0.34 0.54 0.26 0.45 0.62 Partial wedge angleϕ_(x) in region for display mrad 0.42 0.65 0.32 0.44 0.60 Partial wedgeangle ϕ_(y) in region R Partial wedge angle A_(x) in first partialregion mrad 0.45 0.68 0.34 0.43 0.58 for display Partial wedge angleA_(γ) in first partial region Partial wedge angle B_(x) in secondpartial region mrad 0.41 0.65 0.32 0.46 0.60 for display Partial wedgeangle B_(y) in second partial region Partial wedge angle C_(x) in thirdpartial region mrad 0.39 0.62 0.30 0.40 0.61 for display Partial wedgeangle C_(y) in third partial region Difference between maximum value andminimum mrad 0.11 0.13 0.10 0.14 0.13 value of partial region ψ |A_(x) −ϕ_(x)| and |A_(y) − ϕ_(y)| mrad 0.03 0.03 0.02 0.01 0.02 |B_(x) − ϕ_(x)|and |B_(y) − ϕ_(y)| mrad 0.01 0.00 0.00 0.02 0.00 |C_(x) − ϕ_(x)| and|C_(y) − ϕ_(y)| mrad 0.03 0.03 0.02 0.04 0.01 Double Visual Double image(focal distance: 2 m) ○○ ○○ ○○ ○ ○ images check Double image (focaldistance: 3 m) ○○ ○○ ○○ ○ ○ Double image (focal distance: 4 m) ○○ ○○ ○○○ ○ Double image (observers with ○○ ○○ ○○ ○ ○ different seated heights)Device Double image (focal distance: 3 m) ○○ ○○ ○ ○ ○

TABLE 4 Comparative Comparative Comparative Example 7 Example 8 Example9 Configuration of interlayer film Three-layer Three-layer Three-layerContour shape FIG. 5 FIG. 5 FIG. 5 Maximum, thickness in interlayer filmμm 1226 1012 1156 Minimum thickness in interlayer film μm 760 760 760Wedge angle θ of whole interlayer film mrad 0.50 0.27 0.43 Partial wedgeangle ϕ_(x) in region for display mrad 0.62 0.33 0.53 Partial wedgeangle ϕ_(y) in region R Partial wedge angle A_(x) in first partialregion for display mrad 0.55 0.30 0.47 Partial wedge angle A_(y) infirst partial region Partial wedge angle B_(x) in second partial regionfor display mrad 0.64 0.32 0.53 Partial wedge angle B_(y) in secondpartial region Partial wedge angle C_(x) in third partial region fordisplay mrad 0.67 0.39 0.58 Partial wedge angle C_(y) in third partialregion Difference between maximum value and minimum mrad 0.12 0.10 0.13value of partial region ψ |A_(x) − ϕ_(x)| and |A_(y) − ϕ_(y)| mrad 0.070.03 0.06 |B_(x) − ϕ_(x)| and |B_(y) − ϕ_(y)| mrad 0.02 0.01 0.00 |C_(x)− ϕ_(x)| and |C_(y) − ϕ_(y)| mrad 0.05 0.06 0.05 Double Visual Doubleimage (focal distance: 2 m) ∘ ∘ ∘ images check Double image (focaldistance: 3 m) x x x Double image (focal distance: 4 m) x x x Doubleimage (observers with x x x different seated heights.) Device Doubleimage (focal distance: 3 m) x x x

FIG. 10 is a figure showing the relationship between the distance fromthe one end of the interlayer film and the deviated thickness. In FIG.10 , the curve P represents the relationship between the distance fromthe one end of the interlayer film that is involved in the presentinvention and the deviated thickness. In FIG. 10 , the curve Qrepresents the relationship between the distance from the one end of theinterlayer film that is not involved in the present invention and thedeviated thickness. The deviated thickness means the difference betweenthe desired thickness of the interlayer film and the thickness of theinterlayer film that is actually measured.

EXPLANATION OF SYMBOLS

-   -   1, 1A, 1B, 1C, 1D, 1E: First layer    -   1Aa, 1Ca, 1Ea: Portion having sectional shape in thickness        direction of rectangular shape    -   1Ab, 1Cb, 1Eb: Portion having sectional shape in thickness        direction of wedge-like shape    -   2, 2B, 2D: Second layer    -   3, 3B, 3D: Third layer    -   11, 11A, 11B, 11C, 11D, 11E: Interlayer film    -   11 a: One end    -   11 b: Other end    -   11Aa, 11Ca, 11Ea: Portion having sectional shape in thickness        direction of rectangular shape    -   11Ab, 11Cb, 11Eb: Portion having sectional shape in thickness        direction of wedge-like shape    -   21: Laminated glass    -   22: First lamination glass member    -   23: Second lamination glass member    -   R1: Region for display    -   R2: Surrounding region    -   R3: Shading region    -   R11: First partial region for display    -   R12: Second partial region for display    -   R13: Third partial region for display    -   51: Roll body    -   61: Winding core

The invention claimed is:
 1. An interlayer film for laminated glass foruse in a laminated glass that is a head-up display, the interlayer filmhaving one end, and the other end being at the opposite side of the oneend, the other end having a thickness larger than a thickness of the oneend, the interlayer film having a region for display corresponding to adisplay region of the head-up display, when three regions obtained byequally dividing the region for display into three in a directionconnecting the one end and the other end are named a first partialregion for display, a second partial region for display, and a thirdpartial region for display in sequence from the one end side, anabsolute value of difference between partial wedge angle A_(x) in thefirst partial region for display, and partial wedge angle φ_(x) in theregion for display being more than 0 mrad and 0.05 mrad or less, anabsolute value of difference between partial wedge angle B_(x) in thesecond partial region for display and partial wedge angle φ_(x) in theregion for display being 0.05 mrad or less, an absolute value ofdifference between partial wedge angle C_(x) in the third partial regionfor display and partial wedge angle φ_(x) in the region for displaybeing more than 0 mrad and 0.05 mrad or less, and the partial wedgeangle A_(x) being the largest among the three partial wedge angles ofthe partial wedge angle A_(x), the partial wedge angle B_(x), and thepartial wedge angle C_(x).
 2. The interlayer film for laminated glassaccording to claim 1, wherein the interlayer film as a whole has a wedgeangle θ of 0.05 mrad or more.
 3. The interlayer film for laminated glassaccording to claim 1, containing a thermoplastic resin.
 4. Theinterlayer film for laminated glass according to claim 1, containing aplasticizer.
 5. The interlayer film for laminated glass according toclaim 1, comprising: a first layer; and a second layer arranged on afirst surface side of the first layer.
 6. The interlayer film forlaminated glass according to claim 5, wherein the first layer contains apolyvinyl acetal resin, the second layer contains a polyvinyl acetalresin, and a content of a hydroxyl group of the polyvinyl acetal resinin the first layer is lower than a content of a hydroxyl group of thepolyvinyl acetal resin in the second layer.
 7. The interlayer film forlaminated glass according to claim 5, wherein the first layer contains apolyvinyl acetal resin, the second layer contains a polyvinyl acetalresin, the first layer contains a plasticizer, the second layer containsa plasticizer, and a content of the plasticizer in the first layerrelative to 100 parts by weight of the polyvinyl acetal resin in thefirst layer is larger than a content of the plasticizer in the secondlayer relative to 100 parts by weight of the polyvinyl acetal resin inthe second layer.
 8. The interlayer film for laminated glass accordingto claim 1, wherein the partial wedge angle C_(x) is the smallest amongthe three partial wedge angles of the partial wedge angle A_(x), thepartial wedge angle B_(x), and the partial wedge angle C_(x).
 9. Theinterlayer film for laminated glass according to claim 1, wherein thepartial wedge angle A_(x) is larger than the partial wedge angle φ_(x),and the partial wedge angle C_(x) is smaller than the partial wedgeangle φ_(x).
 10. The interlayer film for laminated glass according toclaim 5, further comprising: a third layer arranged on a second surfaceside opposite to the first surface of the first layer.
 11. Theinterlayer film for laminated glass according to claim 1, wherein theinterlayer film as a whole has a wedge angle θ of 0.54 mrad or less.